Make Interval Parsing More Permissive

**Describe the bug**

While working on https://github.com/apache/datafusion/pull/12448 I noticed that the string `5 day hour` is not interpreted correctly by `parse_interval_month_day_nano_config`, it should be considered the same as `5 day 0 hour`, instead it return an error.

**To Reproduce**

run that function, or look at https://github.com/apache/datafusion/pull/12448

**Expected behavior**

`parse_interval_month_day_nano_config` should match postgres behaviour in general

**Additional context**

Related to #6211 where I improved interval parsing a lot, although apparently not enough.

Start at the parse_interval_month_day_nano_config entry point and reproduce the `5 day hour` case described in the issue, using PR #12448 and related issue #6211 for context. Compare the result with the stated PostgreSQL behavior; done means `5 day hour` is accepted as equivalent to `5 day 0 hour` and interval parsing remains correct for existing cases.

Written by the indexing model from the issue text.