refactor: refactor internal packages

[ghost]

As discussed with @JeyJeyGao, this PR completes the refactoring work for Notation internal packages.

The idea is, any package directly related to command shall be put under cmd/notation/internal dir, whereas packages related to functioning and logic shall be put under internal.

Resolves #1151

[codecov]

Codecov Report

Attention: Patch coverage is 85.87571% with 25 lines in your changes missing coverage. Please review.

Project coverage is 76.13%. Comparing base (fb9dbf7) to head (8bb1fbb).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/notation/internal/verify/verify.go	76.92%	7 Missing and 2 partials ⚠️
cmd/notation/cert/list.go	84.21%	2 Missing and 1 partial ⚠️
cmd/notation/internal/flag/options.go	81.25%	2 Missing and 1 partial ⚠️
cmd/notation/internal/sign/sign.go	72.72%	2 Missing and 1 partial ⚠️
cmd/notation/key.go	85.71%	2 Missing and 1 partial ⚠️
cmd/notation/blob/sign.go	85.71%	1 Missing ⚠️
cmd/notation/internal/display/handler.go	90.00%	1 Missing ⚠️
cmd/notation/list.go	75.00%	1 Missing ⚠️
cmd/notation/registry.go	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1205      +/-   ##
==========================================
- Coverage   76.24%   76.13%   -0.12%     
==========================================
  Files          70       66       -4     
  Lines        3637     3628       -9     
==========================================
- Hits         2773     2762      -11     
- Misses        668      669       +1     
- Partials      196      197       +1     

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[JeyJeyGao]

LGTM

[Copilot]

PR Overview

This PR refactors the internal packages by reorganizing command‐related packages under cmd/notation/internal and moving functional logic into internal. Key changes include updating package names and import paths, consolidating duplicate functionalities, and aligning flag options and display handling with the new package structure.

Reviewed Changes

File	Description
cmd/notation/internal/sign/sign_test.go	Updated package name and import paths to reflect refactoring.
cmd/notation/internal/flag/options.go	Renamed package from cmd to flag and updated configuration usage.
cmd/notation/cert/list.go	Replaced deprecated ioutil.PrintCertMap with local printCertMap.
cmd/notation/internal/sign/sign.go	Updated import paths for flag options and removed unused deps.
cmd/notation/internal/display/display.go	Updated package comment and documentation for display handling.
(Other files)	Consistent refactoring of flag, signer, display, and command logic.

Copilot reviewed 52 out of 52 changed files in this pull request and generated 1 comment.

[Copilot]

PR Overview

This PR refactors the internal packages to improve the separation between command‐related and logic/utility packages, as discussed with @JeyJeyGao.

• Relocates packages directly related to commands under cmd/notation/internal (e.g. sign, flag, display) while keeping logic and configuration packages under internal or new subdirectories.
• Updates import paths, flag handling, and test references accordingly, and removes legacy code such as the old output format options.

Reviewed Changes

File	Description
cmd/notation/internal/sign/sign_test.go	Renames package from “signer” to “sign” and updates flag usage to reflect the new path.
cmd/notation/cert/list.go	Replaces references to internal cmd with the new flag package and updates certificate printing logic.
cmd/notation/internal/flag/options.go	Moves the file from the “cmd” package to the “flag” package and refactors output flag handling.
cmd/notation/internal/sign/sign.go	Updates import paths to use the flag package and refactors key resolution logic accordingly.
cmd/notation/internal/display/display.go	Revises package documentation/comments and updates the confirmation function implementation.
cmd/notation/internal/display/output/format.go	Renames the package from “option” to “output” and defines output format constants.
cmd/notation/internal/display/output/print.go	Adjusts comments and renames for improved clarity.
cmd/notation/blob/verify.go	Updates import paths and flag usage in preparation for refactored key verification.
cmd/notation/inspect.go	Updates flag usage and output format handling for the inspect command.
cmd/notation/blob/inspect.go	Replaces usage of legacy option flags with the new flag package for inspection.
cmd/notation/internal/flag/flags.go	Adjusts configuration loading to make use of the new config package.
cmd/notation/internal/flag/options_test.go	Renames the package to “flag” to reflect the updated internal structure.
cmd/notation/inspect_test.go	Updates test expectations to match new error messages and flag parsing behavior.
cmd/notation/internal/display/handler.go	Updates the NewInspectHandler and NewBlobInspectHandler functions to use new output formats.
cmd/notation/blob/sign_test.go	Refactors test cases to use the updated flag package instead of the legacy cmd package.
cmd/notation/blob/sign.go	Replaces internal references (e.g. signer, confirmation routines) with updated flag and display packages and updates error messages accordingly.
cmd/notation/cert/show.go	Switches from the internal cmd package to the updated flag package for logging options.
cmd/notation/blob/policy/import.go	Updates the confirmation prompt to use the new display package for consistency.
cmd/notation/internal/option/format.go	Removes legacy code that has been superseded by the new flag/output refactoring.

Copilot reviewed 52 out of 52 changed files in this pull request and generated no comments.

[shizhMSFT]

LGTM

[shizhMSFT]

LGTM

[JeyJeyGao]

LGTM