Add regex search to find and replace
This issue is duplicated in the Ketida repo: https://gitlab.coko.foundation/ketida/ketida/-/issues/586
Context
Regex search is so incredibly useful for the editorial process. Especially in OEN when authoring and editing is expected to be done in the editor. For example it's amazing for an editor to be able to find all four digit numbers separated by a hyphen with any four digits following them, to help make sure all dates are separated by an En dash instead of a hyphen. 6 hours just turned into 30 minutes of work.
There are many other examples where regex is amazing and I'm sure in time more and more editors will become acquainted with it.
Proposal
Add regex search and replace to the editor find and replace, which can be turned off and on. By default it's off.
Add basic regex guidance in the docs.