apacheGH-38572: [Docs][MATLAB] Update arrow/matlab/README.md with the latest change. (apache#47109)

### Rationale for this change

The documentation for the MATLAB interface hasn't been updated in a while and is out of date.

This PR includes several miscellaneous updates and enhancements to the documentation.

### What changes are included in this PR?

1. Updated the display output for the various `arrow.*` types used in the code snippets in [matlab/README.md](https://github.com/apache/arrow/blob/main/matlab/README.md).
2. Updated the table of supported `arrow.array.Array` types in [matlab/README.md](https://github.com/apache/arrow/blob/main/matlab/README.md).
3. Added a link to the [Testing Guidelines](https://github.com/apache/arrow/blob/main/matlab/doc/testing_guidelines_for_the_matlab_interface_to_apache_arrow.md) in the Testing section of [matlab/README.md](https://github.com/apache/arrow/blob/main/matlab/README.md)
4. Added a link to the [Testing Guidelines](https://github.com/apache/arrow/blob/main/matlab/doc/testing_guidelines_for_the_matlab_interface_to_apache_arrow.md) in [matlab_interface_for_apache_arrow.md](https://github.com/apache/arrow/blob/main/matlab/doc/matlab_interface_for_apache_arrow_design.md).

### Are these changes tested?

N/A. 

This is a documentation only change.

I visually inspected the rendered Markdown for all modified documents to ensure they updated contents display as expected.

### Are there any user-facing changes?

Yes.

1. This PR updates the user-facing documentation for the MATLAB interface. [matlab/README.md](https://github.com/apache/arrow/blob/main/matlab/README.md) and [matlab/doc/matlab_interface_for_apache_arrow.md](https://github.com/apache/arrow/blob/main/matlab/doc/matlab_interface_for_apache_arrow_design.md) have been modified as described above in the "What changes are included in this PR?" section.

### Future Directions

1. Consider deleting or re-purposing `matlab/doc/matlab_interface_for_apache_arrow_design.md`. This document is fairly old and may no longer be the most effective way to document the MATLAB interface.
2. Consider using shorter filenames for `matlab_interface_for_apache_arrow_design.md` and/or `testing_guidelines_for_the_matlab_interface_to_apache_arrow.md`.
3. apache#28149 - consider moving code snippets in `README.md` to an `examples/` directory to simplify `README.md`.
4. Consider adding more developer-oriented documentation (e.g. like "`contributing.md`" to help guide and encourage new contributors to the MATLAB interface).
* GitHub Issue: apache#38572

Authored-by: Kevin Gurney <[email protected]>
Signed-off-by: Sarah Gilmore <[email protected]>

Author: kevingurney