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.

Test: No new test required because no functionality was changed.
Change-Id: I0612d0731083548a196911712f6c0adbbc9a5e9a
diff --git a/keystore2/src/authorization.rs b/keystore2/src/authorization.rs
index 81790af..8265dd0 100644
--- a/keystore2/src/authorization.rs
+++ b/keystore2/src/authorization.rs
@@ -16,7 +16,7 @@
 
 use crate::error::Error as KeystoreError;
 use crate::error::anyhow_error_to_cstring;
-use crate::globals::{ENFORCEMENTS, SUPER_KEY, DB, LEGACY_MIGRATOR};
+use crate::globals::{ENFORCEMENTS, SUPER_KEY, DB, LEGACY_IMPORTER};
 use crate::permission::KeystorePerm;
 use crate::super_key::UserState;
 use crate::utils::{check_keystore_permission, watchdog as wd};
@@ -170,7 +170,7 @@
                     .with(|db| {
                         skm.unlock_and_get_user_state(
                             &mut db.borrow_mut(),
-                            &LEGACY_MIGRATOR,
+                            &LEGACY_IMPORTER,
                             user_id as u32,
                             &password,
                         )