[3.12] gh-108550: Speed up sqlite3 tests (GH-108551) (#108566)

gh-108550: Speed up sqlite3 tests (GH-108551)

Refactor the CLI so we can easily invoke it and mock command-line
arguments. Adapt the CLI tests so we no longer have to launch a
separate process.

Disable the busy handler for all concurrency tests; we have full
control over the order of the SQLite C API calls, so we can safely
do this.

The sqlite3 test suite now completes ~8 times faster than before.

(cherry picked from commit 0e8b3fc718c8a1c4de558c553d9e05049c1dbec6)

Co-authored-by: Erlend E. Aasland <erlend@python.org>
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>