TypeScript build as a seperate job in the check stage

Currently the check stage does not check for TypeScript compiler errors. At the moment it is possible that the linter runs without problems (because the program is syntactically correct) and even the tests are passing but the build of the images will fail.

Please add a TypeScript build job as part of the check stage even before the linters are running so that we can assure, that the whole project can be build when the check stage passes without errors.

Note: npm build should be used.