[#494] Resolve "sc-tech-task: rename `name` to `contactId` in all relevant protocol store tables"

Closes #494 (closed)

context

• name is what the field is called on SignalProtocolAddress.
  • (it is the equivalent to the identifier field on a SignalServiceEnvelope which is ambiguous between a UUID or an e164 phone number, preferring the former, but falling back to the latter if none is available)
• in general, name is a very confusing variable name!
• in the context of a protocol store, where we have an accountId, it would make the most sense to rename this field contactId (rather than name)
• so: let's do it before we move a whole bunch of data around into a new schema!

changes

• rename name column in identities and sessions tables (along with all indexes and primary keys that used to use the name column)
• rename the AccountsWithAddress exposed interface to be DeviceRecord (to distinguish them from a soon-to-be-implemented interface called ContactRecord which does not include device ids)