More Search UI/UX Enhancements

[JohnAFernandez]

This has a few upgrades to the sexp search system, including:

• Adding "Search for Replacement" to context (right-click) menu
• Adding Ctrl+S as a shortcut to initiate search (and item edit)
• Re-enabling search for numeric sexps (which seems to have been disabled by accident, understandable from how big the original PR was)
• Keeps the search from picking results that have nothing to do with the searched string
• Search results will now show strings that start with the search string first. More work would be required to further improve search, like sorting by how soon the search string appears in the text.
• Double click will also now initiate search or item edit, depending on the node type, if there are no children to expand.

Each feature was individually tested, and I'm open to feedback on adjustments.

Fixes #7604