refactor: extract inspect rendering logic to be display handlers

[JeyJeyGao]

Depends on spec change: #1156

Refactor:

• Extract output formatting logic from the inspect command layer to an isolated display handler layer for processing rendering.
• Add json and tree inspect handlers.

Fix:

• For tree output, make the key names with multiple words separated by space characters rather than capitalizing the words, which is defined in the inspect command spec.
• For json output, default to rendering time in RFC3339 with nanoseconds (Notation expiry, signing time and certificate expiry are accurate to 1 second. Timestamp RFC 3161 can have fraction-of-second time value).

E2E Test:

• inspect signature with timestamp, signature expiry and user metadata (text, json)
• inspect signatures with invalid timestamp (test, json)
• inspect with -o shorthand.

Resolves part of #1151

[codecov]

Codecov Report

Attention: Patch coverage is 88.85135% with 33 lines in your changes missing coverage. Please review.

Project coverage is 74.70%. Comparing base (2920cae) to head (60035a7).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
...notation/internal/display/metadata/tree/inspect.go	87.12%	9 Missing and 4 partials ⚠️
...notation/internal/display/metadata/json/inspect.go	89.32%	8 Missing and 3 partials ⚠️
...md/notation/internal/display/metadata/tree/tree.go	60.00%	4 Missing and 2 partials ⚠️
cmd/notation/inspect.go	85.71%	0 Missing and 2 partials ⚠️
internal/envelope/envelope.go	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1150      +/-   ##
==========================================
+ Coverage   73.30%   74.70%   +1.40%     
==========================================
  Files          53       59       +6     
  Lines        3240     3337      +97     
==========================================
+ Hits         2375     2493     +118     
+ Misses        671      651      -20     
+ Partials      194      193       -1     

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[shizhMSFT]

I noticed that handlers are grouped by command names instead of format types. Although both are acceptable, grouping by format types can have more benefits in the long run, especially we have growing commands but fixed set of format types.

One important point is that grouping by format types make developers easier to have consistent output for a certain format type across all commands.

Also, it is easier to have common utility functions without creating a utility package, which is discouraged.

[JeyJeyGao]

I noticed that handlers are grouped by command names instead of format types. Although both are acceptable, grouping by format types can have more benefits in the long run, especially we have growing commands but fixed set of format types.

One important point is that grouping by format types make developers easier to have consistent output for a certain format type across all commands.

Also, it is easier to have common utility functions without creating a utility package, which is discouraged.

Updated to group the handlers by format types.

[shizhMSFT]

LGTM

[shizhMSFT]

LGTM

[ghost]

LGTM

[ghost]

LGTM

[shizhMSFT]

LGTM