Avoid running SELECT statements twice in Execute SQL tab

This speeds up executing SELECT statements in the Execute SQL tab even
further. Before this the statement was executed twice: once to determine
whether it returns any data and another time to actually get the data.
This is still done after this commit, however the process to determine
whether a statement returns any data is optimised in a way which almost
reduces the runtime of this step to zero.

See issue sqlitebrowser#2165.

Update code according @mgrojo's review

Update Arabic translation (sqlitebrowser#2406)

sqlitebrowser#2405
# Conflicts:
#	src/translations/sqlb_ar_SA.ts

DB Browser for SQLite 3.12.0

Update version number for 3.12.0

Updating version number for 3.12.0-rc1

We're using 3.11.300 for the 3.12.0-rc1, in order to keep
numerically lower than 3.12.0, which will be used for the
actual release.

Only include the build date for nightly builds.

Our alpha and beta releases use patch numbers greater than 99, so
were being caught by the version string check.

Update version number to 3.11.2

The rebuilt macOS installer (v2) was generated from this tag.

Update version number to 3.11.1