add test coverage for basic format of iso8601

[yucer]

The ISO 8601:2004 section 2.3.3 defines a the basic format as values like this: "20010822T030405.321-1100".

The current trinodb support is only for the extended format (values like this "2001-08-22T03:04:05.321-11:00")

Expected behavior:

The unit test defined in #13993 should work. And the values of the basic format should work in every place where the extended format is currently used.