ehn(api): add unregisterLanguage method

[aduh95]

Changes

Currently, there is no way of un-do a registerLanguage operation except re-loading the whole library. Adds a unregisterLanguage method to the public API.

Checklist

• No markup tests, this shouldn't change anything to the markup
• Updated the changelog at CHANGES.md
• Added myself to AUTHORS.txt, under Contributors

[joshgoebel]

Curious: What is your use case for needing to unregister a language? It seem obvious yet we've gotten by without it since inception so I'm curious.

[joshgoebel]

This would also need to be documented in api.rst. Otherwise looks about as I'd expect. :)

[joshgoebel]

As this would be a core API method we'd also probably want at least one test to show that it indeed does what it's expected to do.

[aduh95]

Curious: What is your use case for needing to unregister a language?

Useful for testing, in the test suite we have to remove the module from the cache to remove the test languages added by the other tests:

highlight.js/test/detect/index.js

Lines 3 to 4 in 742e87b

	delete require.cache[require.resolve('../../build')];
	delete require.cache[require.resolve('../../build/lib/core')];

This could be avoided if the other tests were cleaning up their test languages. This is needed to move the test suite to ESM syntax (joshgoebel#1).

[joshgoebel]

This is needed to move the test suite to ESM syntax

Ah, that makes sense since we can't just delete the require cache anymore. :)

[joshgoebel]

@aduh95 Thanks!