feat(tags): adds legacy_tag_formats and ignored_tag_formats settings

[noirbizarre]

Description

This PR add 2 new settings to handle tag formats;

• legacy_tag_formats allowing tag format to change over time while retaining the ability to work with legacy version
• ignored_tag_formats to specify expected tag that should not raise InvalidVersion.

So projects which change tag formats and have expected but non-version tags can have these settings:

tag_format = "v${version}"
legacy_tag_formats = [
	"${version}",
	"project-prefix-${version}",
]
ignored_tag_formats = [
	"stable",
	"other-project-*",
]

By doing so, I had to start grouping tag handling and introduce a tags.TagRules object which is responsible for handling all tags rules, initially spread over tag_format, version_schemes and version_providers

Checklist

• Add test cases to all the changes you introduce
• Run ./scripts/format and ./scripts/test locally to ensure this change passes linter check and test
• Test the changes on the local machine manually
• Update the documentation for the changes

Expected behavior

• I can change tag format and still being able to:
  • bump versions (aka. find the increment and commits range)
  • generate changelog (full, incremental, version range)
• I can generate a changelog without warnings for expected tags

Steps to Test This Pull Request

• create a project
• set version_provider = "scm" (not mandatory but allows testing the full scope)
• bump some versions with an initial tag_format
• move current tag_format in legacy_tag_format and define a new tag_format
• bump a version with changelog:
  • current version should be properly identified
  • increment should properly been found
  • new version should be correct
  • generated changelog generation should be correct (both new and old version formats)
  • new tag should respect the new tag_format

then:

• add random-* to ignored_tag_formats
• tag any commit with random-tag
• run cz changelog
  • there shouldn't be any warning

Additional context

There might be a 2nd PR handling a changelog_version_format setting to customize the version rendering in the changelog so:

• it's not the tag format anymore (problematic with some prefixes, like for monorepos)
• have a uniform version display across tag_format changes

[codecov]

Codecov Report

Attention: Patch coverage is 99.43503% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.66%. Comparing base (120d514) to head (c1f2e4f).
Report is 502 commits behind head on master.

Files with missing lines	Patch %	Lines
commitizen/commands/bump.py	92.85%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1297      +/-   ##
==========================================
+ Coverage   97.33%   97.66%   +0.32%     
==========================================
  Files          42       56      +14     
  Lines        2104     2610     +506     
==========================================
+ Hits         2048     2549     +501     
- Misses         56       61       +5     

Flag	Coverage Δ
unittests	97.66% <99.43%> (+0.32%)	⬆️

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[Lee-W]

wow, this is a huge one. I'll be mostly out for the following month but will try to take a look after I'm back

[noirbizarre]

Yes, I know, sorry. I had this idea long ago, just not had time to cover it all until now.
Actually, this is as of today the main remaining pain point I have. I had to migrate a lot of projects on different tagging conventions in a corporate environment and as of today it involves lots of manual steps as well as features lost.
So 🎉 there it is, this one fixes all my cases (and I'm sure I'm not the only one facing those).

In the meantime, enjoy your holidays !

[woile]

Could you add a tutorial for this case? Otherwise it feels like we are adding a lot of features and it's unclear what a user can do with them.
I'll review it this week 👍🏻

[noirbizarre]

I completed the monorepo tutorial and added a FAQ entry but yes, I can totally write a full tutorial on changing tag convention while keeping backward compatibility 👍🏽