This adds support for saving and loading SQL queries to a .sql text
file to the Execute SQL dialog and Update SQL dialogs.
Effectively, it ports this functionality from the DB Manager plugin
over to the core browser-based database connection facilities.
The UX has been designed to mimic the same functionality from
other standard parts of QGIS, eg the Processing Script Editor. Toolbar
actions are used accordingly, instead of the old text button approach
used in DB Manager.
Sponsored by City of Canning
Adds a toolbar to the Execute SQL window, with common actions
for cut/copy/paste/undo/redo/toggle find/clear
This matches the UI for the Execute SQL dialog to other similar
QGIS dialogs, eg the Processing script editor dialog
