Device Interface Version 75

[marktsuchida]

Let's plan to merge

• MMDevice: adds functions to XYStage and Stage to let them signal whether they use callbacks #808
• PRs fixing the 4 issues listed in List of small issues and PRs that need device interface version to be bumped #642

as DIV 75.

This time I think I will try a new way to organize this:

• Each PR requiring DIV bump will bump the DIV to 75 on their branch
• I will create a merge-train PR that merges all the individual PRs (possibly an octopus merge)
• When we merge the merge-train PR, main atomically gets the DIV bumped and GitHub will mark the individual PRs merged
• The single merge into main will be tagged device-interface-75

I still need to create the PRs for those 4 "small" issues (some do require device cleanup), so the merge will be no sooner than next Monday (Feb 23).