…Foundation#794)

### Fix crash when the pixel format is unknown in frames

### Linked issues
n/a

### Summarize your change.
Save the pixel format when the media is opened and use that as fallback
if the pixel format of some frames can not be detected. This assumes
that there is a pixel format when opening the file and if it does not
have one, it will fail at that point before getting to
`decodeImageAtFrame`.

### Describe the reason for the change.
OpenRV was crashing on some AV1 media because the pixel format was
unknown for all the frames.

### Describe what you have tested and on which operating system.
MacOS

### Add a list of changes, and note any that might need special
attention during the review.

### If possible, provide screenshots.

Signed-off-by: Cédrik Fuoco <[email protected]>
Signed-off-by: Cédrik Fuoco <[email protected]>

…cademySoftwareFoundation#958)

### Pin the commit for OpenGL-Registry (downloaded when building GLEW)

### Linked issues
n/a

### Summarize your change.

To fix this, `glew.cmake` will clone the `OpenGL-Registry` and checkout
the latest working commit before executing the `make` command. It will
prevent the build system of GLEW to checkout the master of
`OpenGL-Registry`, and it will continue as usual.

### Describe the reason for the change.
A recent changes in https://github.com/KhronosGroup/OpenGL-Registry
(KhronosGroup/OpenGL-Registry@d38ff69)
is causing C++ redefinition of typedef which causes a bunch of errors.

See an opened issue in GLEW repository:
nigels-com/glew#449

### Describe what you have tested and on which operating system.
CI

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Signed-off-by: Cédrik Fuoco <[email protected]>

Signed-off-by: Cédrik Fuoco <[email protected]>