Add custom transforms to convenience functions, and other API improvement

[jdeschamps]

Description

Following https://github.com/CAREamics/careamics/issues/231, there is a lack of flexibility in the way users can specify the transforms in the config convenience functions. The choice to users comes down to using only the default augmentations or no augmentation at all.

In passing, I also added the dataloader_params parameter by request of students during the MBL course.

This PR does a few things:

• Refactor TRANSFORMS_UNION type in its own module in order to find it more easily.
• Add an augmentations parameter that allows user to pass non-default augmentations.
• Remove use_augmentations.
• Type explicitely the Pydantic trnasfroms
• Add dataloader_params to allow setting PyTorch dataloader parameters (as expected by the configuration).
• Rename model_kwargs to model_params for clarity.
• Refactor the convenience functions and tests in order to minimize duplicated code.

Summary:

• What: Allow users to pass non-default augmentations and dataloader parameters.
• Why: Enable cases where augmentations are useful but need to be different from the default ones (e.g. no rotations), and cases where users might want to add some dataloader parameters.
• How: Added two new parameters to the convenience functions.

Changes Made

• Addded: transform_union.py to hold TRANSFORMS_UNION.
• Modified: configuration_factory.py, corresponding tests and the imports of TRANSFORMS_UNION.

Related Issues

• Fixes https://github.com/CAREamics/careamics/issues/231

Breaking changes

Any call that uses the convenience functions together with the parameter model_kwargs.

This PR will require an update to the doc and the examples.

---

Please ensure your PR meets the following requirements:

• [x] Code builds and passes tests locally, including doctests
• [x] New tests have been added (for bug fixes/features)
• [x] Pre-commit passes
• [ ] PR to the documentation exists (for bug fixes / features)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 87.06%. Comparing base (929b9b8) to head (2963f62).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #239 +/- ## ========================================== - Coverage 87.20% 87.06% -0.15% ========================================== Files 131 129 -2 Lines 4956 4940 -16 ========================================== - Hits 4322 4301 -21 - Misses 634 639 +5 ```

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[jdeschamps]

I typed the transforms differently in the end, and added further refactoring and some error raising!