Summary:
1. Add indent guidess to all tree depths
2. Monospaced font
3. cleaned up alignment of icons
4. Gave everything a bit more space to breathe
Changelog: UI Debugger Tree UI refresh, added indent guides and fixed alignment
Reviewed By: mweststrate
Differential Revision: D47626869
fbshipit-source-id: e4509621cda6c254f7dd5a7ec9b99c13efb577f4
0e15dce033