R1:1e3d1271ada0

Make push log "flags", "reject code" human readable; add crumbs to pull/push logs

Summary:
Depends on D18972. Ref T13049.

Currently, the "flags" columns renders an inscrutible bitmask which you have to go hunt down in the code. Show a list of flags in human-readable text instead.

The "code" column renders a meaningless integer code. Show a text description instead.

The pull logs and push logs pages don't have a crumb to go back up out of the current query. Add one.

Test Plan: Viewed push logs, no more…