Create a regression Test

#### Regression test overview

- [x] Use LJ, maybe 10000 sentence sample
- [x] run new-project with a canned --resume-from file
- [x] preprocess
- [x] train fs2
- [x] train a vocoder on same
- [x] synthesize a bunch of stuff
- [x] run the demo -- maybe use playwright to enter a couple sentences to synthesize

#### Synthesis variants to include

- [ ] synthesize with all output types
- [ ] synthesize from text (characters, phonemes, phonological features)
- [x] synthesize from spectrograms
- [ ] try synthesizing spectrograms and then running vocoder fine-tuning on the generated spectrograms