Bugfix/issue 4 predict incorrect channels

[Andrea-Papaleo]

1. Updates image upload to handle files of images containing a dissimilar number of channels.

• Uses a context provider to wrap app at top level, and a hook to use the upload function.
• The file upload state is contained within the context provider, as is the image shape dialog component.
• Components only need to import and use the function provided by the hook to upload images.

2. Fixes dicom loading with the caveat that some multi-plane images throw errors

• Updates the list of acceptable dicom file extensions
• Can handle multiplane images, though throws error when parsing dicom files with a TransferSyntaxUID = 1.2.840.10008.1.2.4.51 which corresponds to a JPEG baseline encoding

3. Sets project channels when images or projects are loaded
4. Checks agains project channels when selecting segmentation model, disabling incompatible options