feat(mon-pages): offer values in the string filter

A column that knows what values exist can hand the string filter a
`suggest` callback, which turns its plain text field into the chip
autocomplete. One pick stays the `contains` condition it always was,
several become an `or` of one each, so the API sees nothing new.

A column that names no callback is untouched and stays free text.

The UCL page grows a Labels column showing it, keys first and a
wildcard entry, against a stand-in for an autocompleter.

CMK-38149

Change-Id: Ica019a13219ec0160547cadb1389c46b9ba060f2