Add a CLI script for scrubbing email addresses etc from export files

[tellyworth]

We could periodically use this on the server side to generate sample export files.

I used DomDocument rather than regexes to better deal with large files and unexpected whitespace etc.

[tellyworth]

@iandunn mentioned the idea of taking an allowlist approach to scrubbing, rather than scrubbing selected elements like I've done here. That's a good idea for future, especially if we were to reuse this for other sites. That was my other reason for using DomDocument - we could traverse every node and scrub everything that's not explicitly allowed.

If you think this is ok as a starting point let's merge it and add some handbook imports.

[iandunn]

Suggested change

	fclose( $fp_out );
	fclose( $fp_out );
	readline( "\nMake sure you manually review the diff before committing this to the repository! This script might have missed some PII. \n" );

[iandunn]

Here's an example of a safelist approach, for future reference:

https://github.com/iandunn/regolith/blob/824b999c11fae10c4777b8f517df63c6e6fd0a0d/bin/sync-production-content.sh#L91-L164

It works on a SQL dump rather than WRX, but has safelists of various data that might be useful.

[tellyworth]

This is probably not needed now but worth keeping for future use.