GafferImageUI: Add DWA compression presets
GafferImageUI: Add DWA compression presets

Add dwaa and dwab to ImageWriter exr compression preset.

Closes #3152

andrewkaufman/gaffer,boberfly/gaffer,johnhaddon/gaffer,boberfly/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,hradec/gaffer,ImageEngine/gaffer,lucienfostier/gaffer,hradec/gaffer,boberfly/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,lucienfostier/gaffer,ImageEngine/gaffer,appleseedhq/gaffer,hradec/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,boberfly/gaffer,ImageEngine/gaffer,lucienfostier/gaffer,hradec/gaffer,johnhaddon/gaffer,lucienfostier/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,hradec/gaffer