[adamtheturtle]

Source-analysis tools currently have to define a placeholder docutils directive and custom option_spec just to extract arbitrary options and body offsets. Allow parse_directive_text(None, first_line, content) to parse the syntax without a directive schema, retaining string values and syntax diagnostics.

Make DirectiveParsingResult generic and type the schema-free overload as DirectiveParsingResult[str]. Calls with a directive class or full-YAML mode keep support for arbitrary converted values. Existing directive validation and rendering behavior is unchanged.

Closes #1232.

This removes the abstract directive, custom option mapping and Pylint/Pyright suppressions from the downstream integration in adamtheturtle/sybil-extras#1369.

Validation:

• tox -e py311-sphinx9: 1,575 passed, 11 skipped.
• tox -e mypy,ruff-check,ruff-fmt and pre-commit run --all-files: passed.
• tox -e docs-clean -- -T: passed with warnings treated as errors.
• Downstream: 1,007 tests with 100% line/branch coverage and all four type checkers passed using the simplified adapter without suppressions.