[Proposal] Allow open boundaries when some of them are undefined for DatetimeIndex
#### Problem description
When creating a `DatetimeIndex` partially-bounded, i.e., only specifying either `start` or `end` the use of a `closed` parameter different from `None` was intended to be disallowed. This behaviour is bugged as shown in #23198. #23199 solves this bug.

Before #23199, the DatetimeIndex was successfully created. The result contained one less than the requested `periods` in some cases as shown in #23176.

After #23199, a `ValueError` will be raised as it seemed to be intended.

The proposal is to allow `closed` parameters different to `None` for partially-bounded `DatetimeIndex`es. The behaviour should be as defined in the following table

Periods | Ommited parameter | Closed | Current number of items | After #23199 | Proposed number of items
-|-|-|-|-|-
N | `end` | `None` | N | N | N
N | `end` | `"left"` | N-1 | `ValueError` | N
N | `end` | `"right"` | N | `ValueError` | N
N | `start` | `None` | N | N | N
N | `start` | `"left"` | N | `ValueError` | N
N | `start` | `"right"` | N-1 | `ValueError` | N