[mob][photos] Create ConflictAlgorithm enum and stop using it from sqflite

mobile/lib/db/files_db.dart

@@ -16,7 +16,8 @@ import "package:photos/models/metadata/common_keys.dart";
 import "package:photos/services/filter/db_filters.dart";
 import 'package:photos/utils/file_uploader_util.dart';
 import "package:photos/utils/primitive_wrapper.dart";
-import 'package:sqflite/sqflite.dart';
+import "package:photos/utils/sqlite_util.dart";
+// import 'package:sqflite/sqflite.dart';
 import 'package:sqlite_async/sqlite_async.dart' as sqlite_async;
 
 class FilesDB {

mobile/lib/utils/sqlite_util.dart

@@ -0,0 +1,39 @@
+enum ConflictAlgorithm {
+  /// When a constraint violation occurs, an immediate ROLLBACK occurs,
+  /// thus ending the current transaction, and the command aborts with a
+  /// return code of SQLITE_CONSTRAINT. If no transaction is active
+  /// (other than the implied transaction that is created on every command)
+  /// then this algorithm works the same as ABORT.
+  rollback,
+
+  /// When a constraint violation occurs,no ROLLBACK is executed
+  /// so changes from prior commands within the same transaction
+  /// are preserved. This is the default behavior.
+  abort,
+
+  /// When a constraint violation occurs, the command aborts with a return
+  /// code SQLITE_CONSTRAINT. But any changes to the database that
+  /// the command made prior to encountering the constraint violation
+  /// are preserved and are not backed out.
+  fail,
+
+  /// When a constraint violation occurs, the one row that contains
+  /// the constraint violation is not inserted or changed.
+  /// But the command continues executing normally. Other rows before and
+  /// after the row that contained the constraint violation continue to be
+  /// inserted or updated normally. No error is returned.
+  ignore,
+
+  /// When a UNIQUE constraint violation occurs, the pre-existing rows that
+  /// are causing the constraint violation are removed prior to inserting
+  /// or updating the current row. Thus the insert or update always occurs.
+  /// The command continues executing normally. No error is returned.
+  /// If a NOT NULL constraint violation occurs, the NULL value is replaced
+  /// by the default value for that column. If the column has no default
+  /// value, then the ABORT algorithm is used. If a CHECK constraint
+  /// violation occurs then the IGNORE algorithm is used. When this conflict
+  /// resolution strategy deletes rows in order to satisfy a constraint,
+  /// it does not invoke delete triggers on those rows.
+  /// This behavior might change in a future release.
+  replace,
+}