Provide better value editors for certain Library Settings

[Galen Charlton]

There are some library settings that would benefit from providing a better control with which to edit its value.

For example, "Custom CSS for the OPAC" would benefit from at having its input be at least a textarea, or even something that offers syntax highlighting and checking.

Others that could benefit from custom value input widgets include:

- all of the ones whose datatype is "array", including "Staff Catalog Search Filters"
- all of the ones that want a regular expression
- all of the ones that want a URL
- the ones that expect JavaScript snippets
- date and time formats

[Jane Sandberg (sandbergja)]

Confirmed, it is not very ergonomic to enter a whole bunch of css into one tiny single-row input.