Bug 32613: Add autocomplete to SQL reports editor

Bug 32613: Add autocomplete to SQL reports editor

This adds auto-complete for the sql reports editor codemirror instance.
To prevent a regression in syntax highlighting the overlay mode
'sqlPlaceholders' has been removed and replaced with a highlighting
engine that works correctly with the autocomplete engine.

Test Plan:
1. Navigate to reports and create a new sql report
2. Write an Sql query and observe that there is no autocomplete options
3. Apply patch
4. Write a new Sql query and observe that there are now auto-complete
   options that can be navigated through with the arrow keys and
   accepted with either tab or the enter keys.
5. Ensure that items bounded in << >> or [[ ]] are still syntax
   highlighted post-patch

Signed-off-by: Andrew Fuerste-Henry <andrewfh@dubcolib.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>