Add dependency between "sign type" and individual modules

[kchall]

If "sign type" is set to be "1 hand," then the movement, location, hand configuration, and orientation modules should open with "Hand 1" selected by default, but both "Hand 2" and "Both hands" still available for selection. If the user tries to save the module with "Both hands" selected, a warning message should be given: "The sign type for this sign is 1-handed. Are you sure this module should apply to both hands?" ...with button choices: "Return to edit this module" / "Continue with both hands."

Note that this really does apply only to the "hand" options in these modules -- e.g. a user could still specify an arm or leg movement or location.

The relation module doesn't need to have anything pre-specified; while there are some likely logical options, it's not worth the extra complications.

If "sign type" is set to be "2 hands," nothing should happen, because any individual module could apply to one or both hands.

[kvesik]

We called this a "good second issue" on June 13 2024. Should be a pretty straightforward fix once you understand the underlying data structures.

[kvesik]

Good place to start: ArticulatorSelectionPanel, used in ModuleSelectorDialog.

Also the ModuleSelectorDialog.validate_and_save() function.