Add "uniqueId" parameter to Google Authenticator .proto schema

[hicallmeal]

Opened for #1681.

As mentioned in the issue, this makes no material difference to Aegis's ability to import Google Authenticator data, however, you may wish to include it regardless.

No problem if rejected, given the above.

[hicallmeal]

It just occurred to me that it may be an optional field type, given its nature and the fact that it doesn't come up when trying to reproduce (in the app).

I read on field cardinality but it's not actually clear to me that a non-optional field is in fact not optional (thus required).

I've long assumed many of the parameters (alg, digits, etc) aren't always present in exports and those aren't optionally typed, but I may be misremembering.