Improve handling of recipients keys with 'identities' missing email

[sosnovsky]

: We currently support identities missing email address for public keys of recipients, but compose module assumes emails[0] matches identities[0] but that's not necessarily true. I suggest to refactor this part. Instead of "synchronized" arrays we can have an array of objects of the type returned by Str.parseEmail, it has { email, name, full } -- everything that's required. full is the original identity

Originally posted by @rrrooommmaaa in #5294 (comment)