Make Alert Profiles filter expression drop down lists searchable

[lunkwill42]

We might want to add another issue about search-capabilities in the dropdown. Browsing a list of 1300 items is not fun.

Originally posted by @lunkwill42 in #2908

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Is your feature request related to a problem? Please describe.

When adding a filter expression to an alert profile filter, for some match fields, allowable choices for match values are presented as a dropdown list. One example of this is when adding an expression to match on a specific room.

Some NAV users have more than a thousand equipment rooms. Finding and choosing a specific item in a flat drop-down list of 1000 items is quite tedious, even if the items are sorted alphabetically.

Describe the solution you'd like

A match value presented as a dropdown list of choices should provide a search interface to search for substrings among the choices. NAV supports this for some dropdown lists in other forms. In fact, the dropdown to select match fields before being presented with the match constructor form provides this, despite having a very limited list of choices.