(UI Enhancement) Update default form submission button label to "SUBMIT"

[joyce-x-chen]

Currently, the default form submission button label is "SAVE." In project implementations, there is sometimes inconsistency between the use of "SUBMIT" or "SAVE."

While this label is intentionally configurable, I recommend that the default label be "SUBMIT." "SUBMIT" is a clearer description of the button's function, especially as there is ongoing discussion about a drafting feature that would allow forms to be saved as a draft.

[HenryRae]

Agreed.
I've updated most of the CTA labels here

Other areas that might be affected

E.g here "saving" in the body copy was updated to "submitting"
Cc: @rowo