Improve model filters | Use RadioButtons | Custom modality

[qin-yu]

This PR attempts to improve the PlantSeg Napari GUI:

• Refactor dimensions, modalities, and output types ComboBoxes into a unified component to improve the interface and enhance user experience. This fixes a part of #308:
• Use RadioButtons instead of ComboBox for suitable cases for better visibility of choices and reduce exploration cost for users.
• Allow custom modalities and output types in add-model widget

Model filter

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After:

RadioButtons

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Add custom model

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After:

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 42.85714% with 20 lines in your changes missing coverage. Please review.

Project coverage is 54.21%. Comparing base (b2395ea) to head (8711bde). Report is 5 commits behind head on plantsegv2.

Files with missing lines	Patch %	Lines
plantseg/viewer_napari/widgets/predictions.py	45.45%	18 Missing :warning:
plantseg/viewer_napari/widgets/io.py	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## plantsegv2 #314 +/- ## ============================================== - Coverage 54.26% 54.21% -0.06% ============================================== Files 60 60 Lines 4275 4298 +23 ============================================== + Hits 2320 2330 +10 - Misses 1955 1968 +13 ```

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