Fix testCommandExtractScript in test suite

Find `testDoc.foo` in the right place.
Fix testLoad and testRequire

We are in `core`, so look for the file in correct place.

Note that in the 1.9 mode, `$"` contains absolute paths, so we need to
tweak the last assertion in `testRequire`.
Fix TestRequire tests

We are in `core` now, so refer to files in `test` as `../test`
Fix ShellLauncherTest

The test script moved.