Keystore 2.0: Rename legacy_migrator to importer.
This refactor serves the disambiguation between the import of legacy
blobs into the sqlite3 database and the migration of keys between
namespaces, which becomes more promient in the light of shared uid
migration.
Ignore-AOSP-First: Cherry-picked.
Bug: 213173772
Bug: 213172664
Bug: 203101472
Test: No new test required because no functionality was changed.
Merged-In: I0612d0731083548a196911712f6c0adbbc9a5e9a
Change-Id: I0612d0731083548a196911712f6c0adbbc9a5e9a
8 files changed