Unified unit & end-to-end testing

[flxst]

This PR

• [x] introduces a new script tests/tests.py, which can be used for both unit and end-to-end testing. (https://github.com/Modalities/modalities/pull/155/commits/6101bb9c5ad7475c1f39afd45164a95b9071104e, https://github.com/Modalities/modalities/pull/155/commits/81cacfa63c29218ad8ffbad5a54589c928bd3606, https://github.com/Modalities/modalities/pull/155/commits/74045d832d699ef89fa20ff3dc2e8d610a373445, https://github.com/Modalities/modalities/pull/155/commits/e0d0a42c484d7d227cd333f421c92ddbee54b29d, https://github.com/Modalities/modalities/pull/155/commits/563cf27bd1f5bca5fe83caf25fd8f52b68f44421)

  Examples:

  • python tests/tests.py: run CPU tests + single-GPU tests on GPU 0 + multi-GPU tests on GPUs 0/1
  • python tests/tests.py --devices 4,5: same as above but using devices 4/5
  • python tests/tests.py --cpu: run CPU tests
  • python tests/tests.py --single-gpu --devices 3: run CPU tests + single-GPU tests on GPU 3
  • python tests/tests.py --multi-gpu --devices 3,4: run multi-GPU tests on GPUs 3/4

  Note that any GPU device 0-7 can be specified.

• [x] fixes some unit test minor issues (6c4e0f488e68aad2b9b0534291f95a7557392596, 5d2cd148b5376e9cba0a2a3192e66bda90646114)

• [x] fixes all end-to-end tests (all other commits)

[fromm-m]

We should add the pip packaging to pyproject.toml and run once the git pre-commit hooks so that the actions run through, beside that it can be merged.

[flxst]

We should add the pip packaging to pyproject.toml and run once the git pre-commit hooks so that the actions run through, beside that it can be merged.

Will be done as part of #157.