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GH-37234: [MATLAB] Create an abstract `arrow.type.TemporalType` class (#37236)



### Rationale for this change

To simplify the implementation of `Time32Type`, `Time64Type`, `Date32Type`, and `Date64Type`, it would be helpful to create an abstract `arrow.type.TemporalType` class that the date and time types can inherit from.

As a first step, we can modify the implementation of `TimestampType` to inherit from `TemporalType`.

This mimics the class inheritance hierarchy from the C++ libraries.

### What changes are included in this PR?

1. Added a new MATLAB class called `arrow.type.TemporalType`. It inherits from `arrow.type.FixedWidthType` and defines one read-only property: `TimeUnit`.
2. Modified the MATLAB class `arrow.type.TimestampType` to inherit from `arrow.type.TemporalType` instead of `arrow.type.FixedWidthType`.
3. Renamed the  C++ `proxy::TimestampType` methods `timeUnit()` and `timeZone()` to `getTimeUnit()` and `getTimeZone()`.

### Are these changes tested?

Yes. The existing tests in `tTimetampType.m` cover these changes.

### Are there any user-facing changes?

No.

### Future Directions

1. Add `arrow.type.Time32Type` (#37231)
2. Add `arrow.type.Time64Type` (#37225)
3. Add `arrow.type.Date32Type` (#37229), 
4. Add `arrow.type.Time64Type` (#37230).
5. Add `arrow.array.Time32Array`
6. Add `arrow.array.Time64Array`
7. Add `arrow.array.Date32Array`
8. Add `arrow.array.Date64Array`
* Closes: #37234

Lead-authored-by: Sarah Gilmore <sgilmore@mathworks.com>
Co-authored-by: Kevin Gurney <kgurney@mathworks.com>
Signed-off-by: Kevin Gurney <kgurney@mathworks.com>