--write: Introduce TransformMixin for Rules

[cognifloyd]

If a Rule wants to opt-in to transforming, or modifying, files, it can add the TransformMixin and implement the transform() method.

from ansiblelint.rules import AnsibleLintRule, TransformMixin


class FooBarRule(AnsibleLintRule, TransformMixin):
    ...
    def transform(self, match: MatchError, lintable: Lintable, data: list|dict|str):
        """Edit `data` to address the `match` identified by this rule in the `lintable` file."""

This wires up the Transformer to look for TransformMixin rules and run their transform() method.

NOTE: This is a minimized version of TransformMixin to highlight the primary TrnasformMixin interface and show how the Transformer will use it. The Transforms need other features and utils which will be added in follow-up PRs.

Commits:

• Stub TransformMixin for Rules
• Run transforms on non-YAML files (eg Jinja)
• Refactor running rule transforms