TBR: Delete blessing roots and store files if an error is encountered when trying to load them into a principal.
TBR: Delete blessing roots and store files if an error is encountered when
trying to load them into a principal.

Also generate a new ecdsa key if an error is encountered trying to load
it from a file.

This is the same change as go/vcl/4812, but wspr has moved repos.

Change-Id: I2baad80f98a72e6b58f88157f98fd27e279d211f

vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref