Describe the bug

Currently, the footer is inset into the margin, and the header has the capability of being inset.

Historically, this seems to be the case so headers/footer don't collide with the music. However, with #9193, that will no longer be an issue.

Furthermore, the current behavior may be confusing. In many applications, the margin is considered the printable area (with the exception of headers/footers in Word/Google Docs). So when you set a 1 inch margin, you'd expect the entire score and all the text to be inside that 1 inch area. This is likely the case for many MuseScore users as there are several issues on the MuseScore forum about this very behavior, and even an unmerged PR #5902.

I intend to fix this in #9193 such that the top of the header and bottom of the footer align to the margin. However, I'm creating this issue for comments and suggestions before I update the PR to fix this and before that PR is merged.

Note: this is a breaking change as compared to MuseScore 3, and that is expected. We do know that there will need to be some way to migrate existing scores.

Now to tag users who may be interested in commenting.

@Jojo-Schmitz @MarcSabatella @oktophonie

Additional context

Related:
https://musescore.org/en/node/296528
https://musescore.org/en/node/293201
#9193
#9043
#5902