Support multiple linting rules

[aemous]

Description of changes:

• Updated interactive and auto-fix mode to support multiple linting rules. The main technical complexity with supporting multiple rules is that as we apply fixes to the script, older linter findings become stale and would need to be
  'refreshed'. We avoid this problem by linting the script one-rule-at-a-time.
• Updated Base64BinaryFormatRule so that it does not require file:// prefix in an argument value to trigger a detection. It now flags all AWS CLI commands.
• Added PaginationRule that flags all AWS CLI commands, and adds --no-cli-paginate as a fix.
• Replaced ScriptLinter class with utility functions. Updated their interface to let callers pass in their own AST.
• Added save and exit mode.
• Added tests for save-and-exit mode and the new PaginationRule.
• Misc. refactoring for maintainability/readability.

Description of tests:

• Ran and passed all tests.
• Manually tested the tool in interactive and auto-fix mode on the example script, and verified correct behavior.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.33%. Comparing base (7854fa9) to head (d90bfde).
⚠️ Report is 1 commits behind head on upgrade-linting-tool.

Additional details and impacted files

@@                  Coverage Diff                  @@
##           upgrade-linting-tool    #9859   +/-   ##
=====================================================
  Coverage                 93.33%   93.33%           
=====================================================
  Files                       209      209           
  Lines                     16807    16807           
=====================================================
  Hits                      15687    15687           
  Misses                     1120     1120           

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[aemous]

Just a note, the pagination linting rule should actually be based around the --no-cli-pager argument instead of the --no-paginate argument. This will be addressed in a follow-up PR, I already have the fix staged locally with the next round of changes.

[kdaily]

Thanks, nice work so far! Mostly a few basic comments and suggestions.

I think the biggest feedback is the main() method is quite long and a bit hard to follow. I would recommend breaking it out into a few helpers to clarify the branching behavior a bit better.