EGL_EXT_image_dma_buf_import / EXT_EGL_image_storage interactions not relevant anymore

#295 is limiting the interaction with EGL_EXT_image_dma_buf_import and EXT_EGL_image_storage based on the fact that the internal storage format can't be specified, and another concern about YUV buffers.

I am fixing the mesa impl of EXT_EGL_image_storage and I don't think the statement is true anymore. DRM fourcc formats [1] has YUV formats, and users are able to detect a YUV format during import and specify `EGL_YUV_COLOR_SPACE_HINT_EXT`. For the internal format, mesa [2] [3] seems to have no issues about that.

I don't know the state of the other linux driver (nvidia), but I'd like to know if this limitation could be lifted from the spec.

[1]: https://elixir.bootlin.com/linux/latest/source/include/uapi/drm/drm_fourcc.h
[2]: https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/gallium/frontends/dri/dri_screen.c#L746
[3]: https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/gallium/frontends/dri/dri_util.c#L1030

Start by reviewing issue #295 and the cited DRM fourcc definitions in drm_fourcc.h, then inspect Mesa's dri_screen.c and dri_util.c references. Determine whether the stated YUV and internal-format limitations still apply across the relevant implementations; done means an agreed resolution about changing the specification.

Written by the indexing model from the issue text.