tvix/store/directoryservice: give traverse_to a better name, rewrite in non-recursive

#270
Opened by flokli at 2023-05-18T06·25+00

See discussion in https://cl.tvl.fyi/c/depot/+/8568.

The naming is a bit bad (maybe something with find_ or descend_ might make more sense?).

It should also be possible to rewrite this in an iterative fashion, and compare the two implementations for readability.