Fix dbt source identifiers with dots

[nkwork9999]

Description

Fixes #5762.

Preserves identifier quoting when dbt source identifiers contain dots or spaces so names like FILENAME.CSV render as a single quoted identifier instead of being parsed as extra table path segments.

Test Plan

• uv run --extra dev --extra web --extra slack --extra dlt --extra lsp make style
• uv run --extra dev --extra web --extra slack --extra dlt --extra lsp make fast-test
• uv run --extra dbt --with dbt-duckdb --with pytest --with pytest-mock --with pytest-xdist pytest tests/dbt/test_config.py::test_quoting tests/dbt/test_config.py::test_source_config_canonical_name_quotes_identifier_with_dot_or_space -q

Checklist

• I have run make style and fixed any issues
• I have added tests for my changes (if applicable)
• All existing tests pass (make fast-test)
• My commits are signed off (git commit -s) per the DCO

[StuffbyYuki]

@nkwork9999 any difference from this PR?

[nkwork9999]

I overlooked it!
Thank you.