Add linting support for all formats supported by djlint (#4920)

* Refactor djlint linter code

This patch moves the code to the `autoload` directory, so it's available
when it's needed by a specific linter. This avoids redundant code when
another format supported by djlint is added.

* Add linting support for all formats supported by djlint

So far, the `djlint` linter in ALE only supported `html`, which is only
one of several file types supported by `djlint`.

This patch adds support for the following file types:

* gohtmltmpl
* handlebars
* htmlangular
* htmldjango
* jinja
* nunjucks

* Add djlint fixer for various HTML template formats

* Supported formats:
    - html
    - htmlangular
    - htmldjango
    - jinja
    - handlebars
    - nunjucks
    - gohtmltmpl

* Add doc entries

* Add vader tests

---------

Co-authored-by: Adrian Vollmer <computerfluesterer@protonmail.com>

doc/ale-htmldjango.txt

@@ -0,0 +1,12 @@
+===============================================================================
+ALE HTML Django Template Integration                   *ale-htmldjango-options*
+
+
+
+===============================================================================
+djlint                                                  *ale-htmldjango-djlint*
+
+See |ale-html-djlint|
+
+===============================================================================
+  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl: