Use high level API on migration_context instead of using low level API directly

Since `migration_context` has `migrations_paths` itself and provides
methods which returning values from parsed migration files, so there is
no reason to use the `parse_migration_filename` low level API directly.

activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

@@ -1061,10 +1061,8 @@ module ActiveRecord
         version = version.to_i
         sm_table = quote_table_name(ActiveRecord::SchemaMigration.table_name)
 
-        migrated = ActiveRecord::SchemaMigration.all_versions.map(&:to_i)
-        versions = migration_context.migration_files.map do |file|
-          migration_context.parse_migration_filename(file).first.to_i
-        end
+        migrated = migration_context.get_all_versions
+        versions = migration_context.migrations.map(&:version)
 
         unless migrated.include?(version)
           execute "INSERT INTO #{sm_table} (version) VALUES (#{quote(version)})"

activerecord/lib/active_record/migration.rb

@@ -1087,10 +1087,6 @@ module ActiveRecord
       migrations.last || NullMigration.new
     end
 
-    def parse_migration_filename(filename) # :nodoc:
-      File.basename(filename).scan(Migration::MigrationFilenameRegexp).first
-    end
-
     def migrations
       migrations = migration_files.map do |file|
         version, name, scope = parse_migration_filename(file)
@@ -1122,11 +1118,6 @@ module ActiveRecord
       (db_list + file_list).sort_by { |_, version, _| version }
     end
 
-    def migration_files
-      paths = Array(migrations_paths)
-      Dir[*paths.flat_map { |path| "#{path}/**/[0-9]*_*.rb" }]
-    end
-
     def current_environment
       ActiveRecord::ConnectionHandling::DEFAULT_ENV.call
     end
@@ -1145,6 +1136,15 @@ module ActiveRecord
     end
 
     private
+      def migration_files
+        paths = Array(migrations_paths)
+        Dir[*paths.flat_map { |path| "#{path}/**/[0-9]*_*.rb" }]
+      end
+
+      def parse_migration_filename(filename)
+        File.basename(filename).scan(Migration::MigrationFilenameRegexp).first
+      end
+
       def move(direction, steps)
         migrator = Migrator.new(direction, migrations)