fix(syntax/#2985): PHP syntax highlights not showing

[bryphe]

Issue: PHP syntax highlights are no longer showing by default

Defect: #2889 upgraded the extensions, but the PHP extension has a new dependency on embeddedLanguages, which our current textmate implementation does not handle correctly

Fix: Remove the embeddedLanguages for now - add a regression / canary test to ensure we don't break this in the future.

Fixes #2985
Tracking embeddedLanguage support in #2998

[nerdo]

There still seems to be an issue with this fix.

I was able to open a single PHP file and see syntax highlighting, but when I open more PHP files in my project, they do not have syntax highlighting.

[nerdo]

I just did a little bit more tinkering and figured out what seemed to break it.

1. Open any number of PHP files
2. Open a file without syntax highlighting (in my case, I opened a Laravel log file)
3. Subsequent files no longer seem have syntax highlighting applied. It doesn't seem to matter if they are PHP files or other types in my case.

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