Consider changing database certificate storage type

[augustuswm]

Certificates are currently accepted and returned as PEM encoded strings, but in the database we store them as bytes. If we are always going to used a string based format, we may want to change our database representation. Though if we intend to accept other formats and serialize an enum of types to a binary form we may not want to change this.

omicron/schema/crdb/dbinit.sql

Lines 397 to 401 in 7fb6cb4

	-- cert.pem file (certificate chain in PEM format) as a binary blob
	cert BYTES NOT NULL,
	-- key.pem file (private key in PEM format) as a binary blob
	key BYTES NOT NULL

Reference: #5078