Refactor consistency check workflow and update docs

[linus-sun]

Summary

Per work outlined here, this updates documentation to reflect the separation of consistency check and identity monitoring as separate components. Users can view how to run the updated consistency check workflow in the updated README, using a custom configuration file. This PR also refactors the repeated portion of the workflow out into cmd/main, rather than the workflow function itself.

This PR depends on #491 and #492. Relevant commits:
ecf7077
70f13d7

Release Note

Configuration updates to consistency check workflow

Documentation

The README has been updated accordingly.

[codecov]

Codecov Report

Attention: Patch coverage is 8.05085% with 217 lines in your changes missing coverage. Please review.

Project coverage is 60.68%. Comparing base (d271ec7) to head (ecf7077).
Report is 132 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/monitor/main.go	0.00%	87 Missing ⚠️
cmd/verifier/main.go	0.00%	38 Missing ⚠️
pkg/rekor/verifier.go	3.33%	29 Missing ⚠️
pkg/rekor/identity.go	40.90%	22 Missing and 4 partials ⚠️
cmd/monitor/config.go	0.00%	23 Missing ⚠️
pkg/identity/identity.go	0.00%	14 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #493      +/-   ##
==========================================
- Coverage   64.02%   60.68%   -3.35%     
==========================================
  Files           4       15      +11     
  Lines         303     1175     +872     
==========================================
+ Hits          194      713     +519     
- Misses         78      402     +324     
- Partials       31       60      +29     

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