b9049411a8
In dd32dac60f, the "A" and "B" input socket from the Mix node were
disambiguated, so as not to confuse them with Alpha and Blue.
These messages are used in other nodes and elsewhere in the same
sense, so this commit adds translation contexts to these occurrences
as well.
Pull Request: https://projects.blender.org/blender/blender/pulls/108051