Add Prism JS for syntax highlighting

[malberts]

Refs https://github.com/ProfessionalWiki/ExternalContent/issues/30

• Drops PHP 7.4 support (because it's too annoying to write new code like that, unless there's a hard requirement to keep it)
• Added additional parser function parameters based on SyntaxHighlight:
  • lang: the language name (https://prismjs.com/#supported-languages)
  • line: whether to show line numbers
• If lang is specified then the code syntax highlighter is used
  • Default behavior is still Markdown
  • This allows Markdown to be rendered as code too
• Includes a copy plugin which shows a button when hovering over the code

Follow-up TODOs:

• Update syntax highlight CSS to match SyntaxHighlight extension (as close as possible, might not be 100% due to differen tokenization)

Nice to have TODOs:

• Auto-detect the language based on file extension (if lang is not specified)
• Improve how Prism JS/CSS is included. Currently it is this bundle downloaded from their website.
• Make copy plugin optional? Probably an additional copy parameter like line.
• Allow using other Prism plugins?

[malberts]

This wikitext

==Markdown==
===No args (=Markdown)===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/README.md}}
===lang===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/README.md|lang=markdown}}
===lang,line===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/README.md|lang=markdown|line}}

==Python==
===No args (=Markdown)===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.py}}
===lang===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.py|lang =python}}
===lang,line===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.py|lang=python|line}}

==Typescript==
===No args (=Markdown)===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.ts}}
===lang===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.ts|lang= typescript}}
===lang,line===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.ts|lang=typescript|line}}

==HTML==
===No args (=Markdown)===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.html}}
===lang===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.html|lang=html}}
===lang,line===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.html|lang = html|line}}
===Broken===
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/testhtml|lang=html}}

==No language==
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.py|lang=    |line}}
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.ts|lang|line=}}
{{#bitbucket:http://bitbucket:7990/projects/TEST/repos/test/browse/test.html|lang=|line=foo}}

renders this:

[JeroenDeDauw]

So {{#embed:foobar.php}} will still render the PHP as markdown? (Not a regression so not a blocker)

Drops PHP 7.4 support (because it's too annoying to write new code like that, unless there's a hard requirement to keep it)

Yes, nice to drop 7.4

line: whether to show line numbers

Is that the same parameter name as used by the MW extension? line makes me think about what lines should be shown or highlighted. Something like showLineNumbers would be more clear, though harder to remember.

I'm also a bit concerned about adding code specific parameters lang and line to a generic embed function. But I don't see how to improve on the situation.

[malberts]

So {{#embed:foobar.php}} will still render the PHP as markdown? (Not a regression so not a blocker)

Yes. That's basically this TODO in the code: https://github.com/ProfessionalWiki/ExternalContent/pull/32/files#diff-4e52f3cf52e1f852c9ae649d8efeef9f7c7953d4ef619a21b4c1bdb93b2d0d15R30

It's simple enough to just check if the extension is not .md, so if it makes sense for the default behavior then it's quick to do.

Is that the same parameter name as used by the MW extension? line makes me think about what lines should be shown or highlighted. Something like showLineNumbers would be more clear, though harder to remember.

Yes: https://www.mediawiki.org/wiki/Extension:SyntaxHighlight#line. That extension uses highlight for specifying lines to be highlighted. I have no particular preference for the SyntaxHighlight names, I just used that for similarity.

I'm also a bit concerned about adding code specific parameters lang and line to a generic embed function. But I don't see how to improve on the situation.

I couldn't come up with a better approach. Unless we split the embed and bitbucket functions into a further embed-code and bitbucket-code, or something along those lines.

[JeroenDeDauw]

It's simple enough to just check if the extension is not .md, so if it makes sense for the default behavior then it's quick to do.

Getting behavior that is consistent, convenient, and reasonably in line with existing 1.x behavior seems challenging. Too difficult without sleep first.

[malberts]

I'll do a follow-up with code improvements.