Fix ImageIOReader for images with channels and reordered axes

[jstriebel]

This fixes the ImageIOReader to recognize channels and report them correctl in images.sizes. Also, the frame_shape implementation is removed, since it did not account for reordered axes via bundle_axes. It would be great if a @soft-matter maintainer could add a test-case, e.g. using scifio-test.jp2 from https://samples.scif.io/test-jpeg2000.zip.

The current behavior looks like this:

>>> import pims
>>> = pims.open("scifio-test.jp2")
>>> p.shape  # correct
(1, 500, 500, 3)
>>> p[0].shape  # also correct
(500, 500, 3)
>>> p.sizes  # c missing!
{'x': 500, 'y': 500, 't': 1}
>>> p.bundle_axes="cxy"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/jonathan/.cache/pypoetry/virtualenvs/webknossos--lLCZL8U-py3.9/lib/python3.9/site-packages/pims/base_frames.py", line 524, in bundle_axes
    raise ValueError("axes %r do not exist" % invalid)
ValueError: axes ['c'] do not exist
# and even after setting up the c axis, the shape is not corrected:
>>> p._init_axis("c", 3)
>>> p.bundle_axes="cyx"
>>> p.shape  # should be 1,3,500,500
(1, 500, 500, 3)