Add `ERB`/`EJS` Grammar

[cengelbart39]

Description

Adds ERB/EJS grammar via tree-sitter-embedded-template.

Related Issues

• #10

Depending on the desire to add more languages to CELanguages, it could close this issue as well.

Checklist

• [x] I read and understood the contributing guide as well as the code of conduct
• [x] The issues this PR addresses are related to each other
• [x] My changes generate no new warnings
• [x] My code builds and runs on my machine
• [x] My changes are all related to the related issue above
• [x] I documented my code

[cengelbart39]

With the current implementation, there are highlighting issues with ERB and EJS.

For ERB, Ruby doesn't highlight properly (left ERB, right Ruby)

While HTML highlighting works, it isn't perfect either, with some closing tags not being highlighted

It's a similar case for EJS, with JavaScript not highlighting, while HTML highlighting is the same as ERB (left EJS, right JS)

While I have mentioned this in the Discord, I felt I should include it here for anyone waiting on this PR to not be a draft anymore.

[cengelbart39]

I updated the PR to keep up with changes to the package since created.

Between updates to CE, CEL, CETX, and CESE, the highlighting issue persists.