Contibutes to https://gitlab.com/gitlab-org/gitlab/-/issues/16950

Follow-up for
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/55669

Extend Gitlab::Diff::Line object with a new `marker_ranges` field.
This field keeps information about ranges of characters for each line
with the type of the change.

Gitlab::Diff::Highlight code was updated to fetch MarkerRanges from
Diff::Line objects.