[SPARK-20482][SQL] Resolving Casts is too strict on having time zone set

## What changes were proposed in this pull request?

Relax the requirement that a `TimeZoneAwareExpression` has to have its `timeZoneId` set to be considered resolved.
With this change, a `Cast` (which is a `TimeZoneAwareExpression`) can be considered resolved if the `(fromType, toType)` combination doesn't require time zone information.

Also de-relaxed test cases in `CastSuite` so Casts in that test suite don't get a default`timeZoneId = Option("GMT")`.

## How was this patch tested?

Ran the de-relaxed`CastSuite` and it's passing. Also ran the SQL unit tests and they're passing too.

Author: Kris Mok <kris.mok@databricks.com>

Closes #17777 from rednaxelafx/fix-catalyst-cast-timezone.