Activity History section of Advanced Search should include dropdown list of existing activity types.

Right now, the Activity History section of the Advanced Search requires the user to type in the name of the Activity Type on which they'd like to search. This forces the user to have to try to remember and accurately enter the names of the different activity types that exist in CiviCRM, which might prove difficult if there are many custom activity types or activity types with similar names.

This would be fixed by having a dropdown list of all existent activity types from which the user would select one, instead of having them type it in.