No equivalent of `--precise` for recursive dependencies

If we treat `cargo upgrade` as a replacement for `cargo update`, #790 provided us limited support for `cargo update --precise` but doesn't help when you want to set it for a recursive / transitive / indirect dependency.

One idea is to integrate this into `cargo generate-lockfile` and have that be a general lock file editing tool.

Review issue #790 and the existing handling of `cargo upgrade` versus `cargo update --precise`. Then examine the `cargo generate-lockfile` entry point and determine how recursive dependency versions could be specified. Done means defining and implementing a clear general lockfile-editing approach for indirect dependencies.

Written by the indexing model from the issue text.