Added Tga image loader to load tga files instead of using QT image wh…

[VickyAtAZ]

…ich can't load many tga formats.

Signed-off-by: Qing Tao [email protected]

What does this PR do?

This PR added TgaLoader which can load a larger set of tga files compare to QImageLoader which was used for loading tga files.

This PR fixes issues in https://github.com/o3de/o3de/issues/10085, https://github.com/o3de/o3de/pull/6507, https://github.com/o3de/o3de/issues/6381, https://github.com/o3de/o3de/issues/2682

This PR is also to replace the PR: https://github.com/o3de/o3de/pull/6507

How was this PR tested?

Unit tests of AtomImageProcessing gem. Tested with tga files from each issues.