It is unlikely this is needed anymore, and as pointed out things should
now safely return OOM if the bitmap is too large to allocate.
Also, no recently added decoders respected this limit anyway.
Fixes#20872
The ideal size is the size the user will display the image. Raster
formats should ignore this parameter, but vector formats can use
it to generate a bitmap of the ideal size.
There was a TODO questioning whether breaking on >4bpp images
was the correct behaviour when RLE4 was detected. There is no
indication in the spec that RLE4 can be used with anything >4bpp,
so I believe this doesn't require additional follow-up.
MS Spec:
https://learn.microsoft.com/en-us/windows/win32/gdi/bitmap-compression
