sc-tech-task: rename `name` to `contactId` in all relevant protocol store tables

• 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!