Better error reporting in CSRApprover

[twz123]

Description

This has been done to ease debugging integration test failures when upgrading to Kubernetes 1.27 (#2879):

Refactor the CSRApprover component in a way that errors are reported in a more structured and detailed way. Let all bool functions return errors instead, so that they can explain what was rejected. Improve the logging of those errors, so that they aren't logged twice and the CSR names are included in the logs. Remove the csrRecognizer on the way, as there is only a single one, and there's no additional ones on the horizon, so this seemed unnecessary, and inlining it makes the approval loop easier to read.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

• Manual test
• Auto test added

Checklist:

• My code follows the style guidelines of this project
• My commit messages are signed-off
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings