By moving the tests subdirectory to t, we gain the ability to run `yath
test` with no arguments from inside `nix develop` in the root of the
the repo.
(`nix develop` is necessary in order to set the proper env vars for
`yath` to find our test libraries.)
This makes the test faster (by removing it and replacing it with a
`TestScmInput` module that exports the `testScmInput` subroutine). Now,
all the input tests can be run in parallel.
Some of the `tests/jobs/*-update.sh` scripts were "broken" (e.g. tests
failed for various reasons on my machine), so I fixed those up as well.
Co-authored-by: gustavderdrache <gustavderdrache@gmail.com>
