Also add test action to build.sh which builds all images and then tests
them by running configure,build,test on each.
Also add new dependencies to web image which Playwright requires.
- use KEYMAN_USE_NVM and KEYMAN_USE_EMSDK
- pre-install node (where necessary) to prevent having to do it on each
build
- adjust to current `master`
- fix a few bugs in the Dockerfile
- get required node version from package.json (through
`shellHelperFunctions.sh`)
