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GH-37228: [MATLAB] Add C++ `ARROW_MATLAB_EXPORT` symbol export macro (#37233)



### Rationale for this change

Currently, the main shared library used by the MATLAB interface - `libarrowproxy` - does not explicitly export any symbols.

This hasn't been a major issue so far based on our usage of these symbols - except for in one case - which was being able to define a template specialization of the static make function for `NumericArray<T>` in a C++ source file. To work around this, we decided to inline these template specializations.

However, this isn't an ideal solution because these functions shouldn't need to be inlined (and, in fact, this could have undesirable performance implications).

In addition, to enable the ability to write C++ unit tests for code in the "Proxy layer", we would need to export symbols from `libarrowproxy`.

This is the first in a series of pull requests in which we will export symbols from `libarrowproxy` so we can write C++ unit tests via the GoogleTest framework.

### What changes are included in this PR?

1. Added a C++ `ARROW_MATLAB_EXPORT` macro for exporting symbols in `visibility.h`
2. Added a new header `timestamp_array.h` which declares the template method specialization of the static `make` function for `NumericArray<arrow::TimestampType>`
3. Moved the definition of `NumericArray<arrow::TimestampType>::make` to `timestamp_array.cc`

### Are these changes tested?

New tests points are not needed. These changes are covered by our existing  test suite.

### Are there any user-facing changes?

No.

### Future Directions

1. As mentioned above, this is the first in a series of pull requests. In future PRs we will export more symbols to enable C++ unit testing.
* Closes: #37228

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