maint(core): exclude `.configured` files from source tarball 🏗️
In the source tarball we don't want to include `.configured` files so that a build will call `npm i` first.
Fixes: #15905
Follows: #15926
- make `verify_source.sh` a full builder script
- make options for `launchpad.sh` less confusing
- reference `--help` in `packaging.md`
- run new script as part of Ubuntu packaging workflow
Co-authored-by: Marc Durdin <marc@durdin.net>
In the source tarball we don't want to include `.configured` files so
that a build will call `npm i` first.
Fixes: #15905
Follows: #15926
Test-bot: skip
This change adds a new GitHub action that verifies that Keyman can build
from the source package. Also check that source package used for Launchpad
and Debian/Ubuntu packaging doesn't produce lintian errors. Previously
lintian errors did go unnoticed because they didn't stop the build.
Also refactor `launchpad.sh` script to be a proper builder script, and add
some new parameters to allow skipping some steps in the script.
Build-bot: skip
Test-bot: skip
