Extension completions

[itepastra]

Add completions for the various htmx extensions. for #14

thanks to @WillLillis for making a framework to add the extensions

TODO:

• [x] add actual documentation for the attributes
• [ ] add actual documentation for the tags
• [ ] make additional tags for existing attributes work (for example: idiomorph adds hx-swap="morph")
• [ ] make tags that don't start with hx- work in the tests (some seem to work correctly in actual files)
• [ ] the classes attribute from class-tools is not completed