Add linting/formatting with djlint

[krukas]

Use https://github.com/djlint/djLint to add support for linting and formatting:

Formatting example: https://pygls.readthedocs.io/en/latest/examples/formatting.html
Linting (diagnostics) examples:

• https://pygls.readthedocs.io/en/latest/examples/publish-diagnostics.html
• https://pygls.readthedocs.io/en/latest/examples/pull-diagnostics.html

[wolflu05]

That is an awesome idea, would really like to have formatting and linting. This would also help us at inventree for our templates.