Partial implementation of #8329.

This is for discussion -- there are a number of issues.

Changes proposed in this pull request:

• Implements basic __arrow_c_array__ and __arrow_c_schema__ support for reading Pillow images in Arrow capable libraries.
• Implements basic arrow array exporting object -> Pillow image. This supports reading arrays in exactly the same formats that we export from Pillow.
• Adds a way to force the internal allocator to use single blocks for images. Previously there is core.new_block, but internal operations call ImageNewDirty internally, which only calls the Arena Allocator.
• Adds C level read-only flag. Currently only exported to python layer, and overrides python read_only.

Issues:

• Currently fails on large images.
  • Returns a ValueError if the image is allocated in multiple blocks
• There's extraneous stuff in Arrow.c that should be cleaned up.
• Some changes in Storage.c aren't required.
• Unclear if we're exporting the most useful version of the data.

Todo:

• Alternate binary installable arrow lib for testing, or loopback only testing on troublesome platforms if we can't find one that works.
• Fix Windows Segfault. I don't have a windows env here, so either I need to figure out a CI based version or I'll need an assist.
  • Windows tests now appear to be passing on 3.10->3.13, with 3.9, pypy3.10 and 3.14 failing on arrow install.
• Python accessible version (r/w, likely) of the schema capsule and possibly array metadata. Partially for testing, partially for sanity checking at the python layer before passing into the C portion.
• Fix the UNDONEs in the code, especially around error handling.
  • make sure we're raising an error if we don't accept the array format.
• Large image support or error out.
• Wire up enforcement of c level read_only flag
• Docs

For Review:

• What CVE is in here that I'm not seeing?
• There's some pretty serious mucking with the object lifetimes, specifically there's now effectively a refcount on the core C image, so it's lifetime is not limited to the python object's lifetime. I think this is required, but it needs review.
• I'm not 100% on how so much of the checking is in Storage.c, vs somewhere closer to the surface.
• The core Imaging item now stores a reference to the array pycapsule, which requires PyINCREF and PyDECREF in Storage.c. This feels like it's finally breaking the wall of libImaging not relying on python headers.