Add Regex Find node

[RunDevelopment]

This adds the Regex Find node, a simple node that just executes a regex and returns the first match.

To make this node more powerful, I also added a text pattern option that allows users to use a text pattern to access the capturing groups of the match.

This should be enough to do some basic parsing for things like file names.

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Other changes:

• I also improved regexReplace to return never for more combinations of invalid inputs.

[joeyballentine]

Nice!