test: elaborate vhdl test and speedup
test: elaborate vhdl test and speedup

Make tests run faster by calling cargo once at the beginning of the
`tests/run.sh` script, then using `target/debug/moore` directly. Also
extend the script to parse `@elab <entity>` comments in the test source
files and elaborate the corresponding entities.

fabianschuiki/moore,fabianschuiki/moore,fabianschuiki/moore,fabianschuiki/moore,fabianschuiki/moore