tree 7859a433b82841167ad2ec5e35480b22ac998576
parent 7b37dc162554009b41d3c8829e074997527e1a61
author Xdng Yng <wyverald@gmail.com> 1708455597 -0800
committer Copybara-Service <copybara-worker@google.com> 1708455702 -0800

Add `rctx.watch_tree()` to watch a directory tree

- Added `rctx.watch_tree()` to watch a directory tree, which includes all transitive descendants' names, and if they're files, their contents.
  -  In the future we could add glob patterns to this method.
- Added a new SkyFunction DirectoryTreeDigestFunction to do the heavy lifting.
  - In the future, for performance, we could try to get this skyfunction to have a mode where it only digests stat(), to use as heuristics (similar to #21044)

Work towards #20952.

Closes #21362.

PiperOrigin-RevId: 608667062
Change-Id: Ibacbb7af4cf4d7628fe8fcf06e2c4fa50e811e4e