timestamp type

[yliuuuu]

Issue #, if available: PartiQL Doc: issue 41

Description of changes:

• Add timestamp literal parsing related tests.
• Modify EXTRACT test cases:
  • all ion timestamp should be consider timestamp with timezone.
  • add tests that use TIMESTAMP literal as EXTRACT parameter.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.