Journaling: search, read and export over JMAP, and the chain check

Phase 4 of the journaling spec.

- inbuxa:JournalEntry/query and /get (sysJournalSearch): filter by time,
  sender, recipient, either, direction, subject words, Message-ID and
  journal, newest first; the whole report only when asked for.
- inbuxa:JournalExport/set (sysJournalExport): a reason is required; a
  ZIP of the matching reports with manifest.csv, exceptions.csv and
  manifest.sha256, up to 10,000 reports and 1 GB.
- inbuxa:JournalVerification/set (sysJournalGet): chains and reports
  rechecked.
- Every search, listing, read, export and check is written to the audit
  log before anything is returned, with existing actions only.
- Catalog entries for the three objects; spec as-built notes.

journal_tests: administrators can't search; a Compliance Officer searches,
lists, reads a report, exports (reason required) and checks the chain;
the officer can't change journals; each of those is in the audit log.

crates/jmap/src/changes/get.rs

@@ -433,6 +433,9 @@ impl IntermediateChangesResponse {
             | MethodObject::MailRule
             | MethodObject::SecurityAcceptance
             | MethodObject::Journal
+            | MethodObject::JournalEntry
+            | MethodObject::JournalExport
+            | MethodObject::JournalVerification
             | MethodObject::HeldMessage
             | MethodObject::ProtocolPolicy
             | MethodObject::TenantProtocolPolicy