bugfix - bazel-diff with depth

Bugfix: actually decrement depth variable each iteration to properly calculate hashes taking the depth into account

bazel-diff with depth

Includes an additional flag, depth, for the generate-hashes command. This specifies an upper bound on the depth of the build graph to hash. If the depth parameter is omitted, the search is unbounded.

Can be used to limit the scope, with respect to locality, of the impacted targets returned.