Regular expression search for metadata fields

[BryonLewis]

1. filename filter for regular expressions

Currenent metadata fields that have more than X unique values are searchable, make sure they also support regular expressions for the filtering.

[BryonLewis]

Looking at the code I noticed that I intentionally escape fields from regex. I think for searchable fields I'm going to add the mdi-regex icon that can be toggled on/off to allow searching using regex. I'm doing this for users who are searching for filenames that contain regex and don't want to escape those fields.