Freetext searches don't allow partial operator matching

For searches using the FreeTextAnalyzer (notably content and diff searcher), if the input contains multiple operator characters (generally special characters like '+', '-', '@', /', etc.) next to each other, either all or none of the operator characters must be specified in the query when searching.

Example:

1. Have a file with the following content:

   >@test
   

2. If searching for >@test, the file is returned
3. If searching for @test, the file is not returned
4. If searching for is-test, the file is returned.