This PR handles template toolkit syntax as a pre-processor step such
that `%]` and `[%` are seen as valid boundary characters.
This is handled for the `.tt`, `.tt2` and `.tx` file extensions. It's
not handled if this syntax is used in `.html` files because then
everybody pays a pre processor cost even if you don't need this syntax
in most cases.
This now ensures that a `template.tx` like this:
```html
<div class="[% IF $is_open %]bg-white/40[% ELSE %]bg-white/10[% END %]"></div>
<!-- ^^^^^^^^^^^ ^^^^^^^^^^^ -->
```
Extracts the classes in between those conditions correctly.
This also fixes a small issue related to Maud, a template engine for
Rust where conditionals like `p.text-black[condition]` caused the
`text-black` class not to be extracted. This is fixed as part of this PR
because it was commented on the linked issue.
Fixes: #20233
## Test plan
1. Added a new extractor
2. Added regression tests
3. All existing tests pass
d5ca0aeac9