rust: Rename get_node methods to data_for_node, get_rev to data_for_rev...
rust: Rename get_node methods to data_for_node, get_rev to data_for_rev
These are respective methods of Changelog, Manifestlog, and Filelog;
three Rust structs that that wrap a Revlog struct.
This rename clarifies that node IDs or revision numbers are parameters,
not return values.
Also reword doc-comments in Manifestlog and Filelog to separate node IDs
and revision numbers that are local to a given (non-changelog) revlog
from those of a changeset.
Differential Revision:
https://phab.mercurial-scm.org/D11416
