Add i386 and arm32v7 building.

Also update to Alpine 3.23.
Move ALPINE_VERSION to workflow.
Allow workflow_dispatch.
Use a docker pull for the image before steps.
Add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 & ninja to mysql57.
Disable broken mysql builds.

Signed-off-by: Satadru Pramanik <satadru@gmail.com>