Feat/add context matcher and export types

[jacobmolby]

Hi, this PR adds a new option translationContextMatcher.

It's purpose is to not split every key up by the contextSeperator, but only remove context suffixes.

In my code base it made the result of the CLI unusable since the keys are snaked case.

Example:

{
   "press_to_deselect": "..."
}

The translationContextMatcher defaults to a regex that should capture the context used by i18n-next in the various versions of their JSON Format. I wasn't sure if anything else existed out there, so I made it configurable.

Besides that I've moved some of the documentation from the README into the RunOptions interface and exported it, allowing users to have autocomplete when creating their config.

I also moved this part [...matchKeysSet].toString() out of the for loop, since it seemed unnecessary to compute the string every iteration.

Let me know if you have any comments.

[mxmvshnvsk]

Hi, thanks for your PR, it's good feature. Already in release 0.15.0.