[MATLAB] Add code architecture diagrams

[asfimport]

Reporter: Fiona La / @lafiona

It would be helpful to add some code architecture diagrams to the MATLAB Interface.

For example, it would be nice to have a visual representation of the way that the MATLAB Interface uses mathworks/libmexclass and Proxy objects to wrap corresponding Arrow C++ types (e.g. arrow::RecordBatch).

_{Note: This issue was originally created as ARROW-12348. Please see the migration documentation for further details.}

[kevingurney]

Switching this from Type: task to Type: enhancement since it is no longer marked as a sub-task of #27758.