rust: implement the `Graph` trait for all revlogs
This is trivial and makes all the algorithms relying on the trait usable
for more use cases.
# Tests to be disabled when building and testing in the Nix sandbox.
# tests enforcing "/usr/bin/env" shebangs, which are patched for nix
test-run-tests.t
test-check-shbang.t
# doesn't like the extra setlocale warnings emitted by the nix bash wrappers
test-locale.t