Fixed #23935 -- Converted decimals to fixed point in utils.numberformat.format
Fixed #23950 -- Prevented calling deconstruct on classes in MigrationWriter.
Fixed #20392 -- Added TestCase.setUpTestData()

Each TestCase is also now wrapped in a class-wide transaction.
Refactored some tests to take advantage of refs #20392.
Fixed #23939 -- Moved session verification out of SessionAuthenticationMiddleware.