Trac #34379: Implement a hook to access free (graded) resolutions

In #33950, free (graded) resolutions for modules over polynomial rings
were added. However, one needs to import a top-level function to do the
construction. The goal of this ticket is to add a method, such as
`free_resolution()`, to these (sub)modules (and ideals) to ease access.

URL: https://trac.sagemath.org/34379
Reported by: tscrim
Ticket author(s): Travis Scrimshaw
Reviewer(s): Kwankyu Lee