- replace use of `kmw` with `keyman`
- unify pattern to load keyboards: do it in `keyman.init().then()` instead
of in the document `onload`
Part-of: keymanapp/keyman.com#449
Test-bot: skip
Note: build.sh updated to make sure that test:help build action:target
doesn't also call test.sh by adding `:_all` meta-target.
Note: CI will need a new help-keyman-com.sh build step to deploy web
engine help.
Fixes: #12347
