feat(otlp): Sigma rules

[MichaelThamm]

Issue

Prepare the SigmaRules class which implements a similar API to the cosl.rules.Rules class.

• methods: add, add_path, as_dict, etc.
• types: SigmaRuleFileFormat, SigmaRuleFormat

Builds on this PR:

• feat: Sigma rules pt.3 cos-lib#197

Solution

Add the feature.

Checklist

• I have added or updated relevant documentation.
• PR title makes an appropriate release note and follows conventional commits syntax.
• Merge target is the correct branch, and relevant tandem backport PRs opened.
• This change warrants a release, so I have updated the project.version field in the pyproject.toml file.

Context

Testing Instructions

Testing of the SigmaRules class is achieved in:

• feat: Sigma rules pt.3 cos-lib#197

This PR adds tests for the charmlib-scoped responsibilities:

• feat: Sigma rules pt.2 #467

Upgrade Notes

[MichaelThamm]

remove when done testing

[MichaelThamm]

remove when done testing