You can log in to a PDS with a DID, and most of PDS MOOver already copes with one because handleAndPDSResolver() accepts DIDs. Two paths did not:
- resolveSource() when a source PDS URL override is given forced the identifier through the handle resolver
- Migrator.deactivateOldAccount() (the Turn Off page) did the same
Both now short-circuit on a did: prefix and use the DID directly, so the
DID document is used to find the PDS instead of trying to resolve a
handle. Also fixes deactivateOldAccount() never actually calling
cleanHandle() (the call was stuck on the end of a comment line).
Labels on the three identifier fields now say "(or DID)". Tests: a mock-atmosphere test for both loginPreflight paths with a DID, and an e2e turn-off test entering the DID (needs the web-ui to pick up this moover build).