GridAlarms continually runs the Alert Query when performing pages actions causing slow reponse

[TheWitness]

Describe the bug

GridAlarms for just about all page actions will rerun the SQL Query. In our case, the SQL Query can run upto a minute making the GridAlarms plugin very inconvenient to use at times.

GridAlarms does this to populate the list of columns available for querying and performing alerting operations on. Instead of running this query continually, cache the columns and invalidate the columns when the Data Source is updated.

Expected behavior

Results should be cache to prevent this issue.

RTM Version
develop