Display library name rather than root if possible
Summary:
Per D26606#42392
I somehow managed to accidentally clobber that diff when landing. I have no idea how I did that, but now we need another diff.
Test Plan: Run `bin/i18n extract`
Reviewers: O1 Blessed Committers, aklapper
Reviewed By: O1 Blessed Committers, aklapper
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Differential Revision: https://we.phorge.it/D26659