bug/Enable a (global) way to set PIL.Image.MAX_IMAGE_PIXELS

[cwang]

Describe the bug
PIL has it's own default max pixels to prevent what they call "decompression bomb DOS attack" - it's 178956970 pixels as it stands now

To Reproduce
Use a very large image exceeding the pixel number

Expected behavior
As a lib, unstructured could expose a new env var to allow downstream to set the max pixels, whose value will be used inside the lib codebase to set PIL.Image.MAX_IMAGE_PIXELS as a result

Screenshots
N/A

Environment Info
N/A

Additional context

Maybe related to #3329