feat(transformer-compile-class): support for custom class names

[Techassi]

This PR adds support for custom compile class names. The current behavior looks like this:

<div class=":uno: font-bold text-white">Foo</div>

Which generates something like this:

.uno-hpseh7{font-weight:700;--un-text-opacity:1;color:rgba(255,255,255,var(--un-text-opacity));}

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The PR adds support to customize the compiled class name. It is still possible to customize the trigger (:<TRIGGER>:) and the prefix (default uno-). The new trigger syntax is: :<TRIGGER>(-NAME):. This allows the following behavior:

<div class=":uno-foo: font-bold text-white">Foo</div>

.uno-foo{font-weight:700;--un-text-opacity:1;color:rgba(255,255,255,var(--un-text-opacity));}

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The custom compiled class name is added to the tokens set. If a duplicate is encountered, an error is thrown.

Note

Unrelated to this PR, but still worth a mention: the playground doesn't pass tokens in the UnocssPluginContext. It is undefined and results in errors when trying to run the compile class transformer. (I guess this also applies to other transformers)

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[Techassi]

Added test. PR should now be ready for review.

[antfu]

Converting to draft for now, let me know when you think are ready. Thanks!

[antfu]

Can we have some tests for it, as well as the custom regex? Thanks

[Techassi]

Added tests in abc2bac.