Improve testing by translating the Matlab C API examples to Rust using matlab-sys

[Tastaturtaste]

Improve testing

Currently only a small subset of the whole Matlab C API gets tested using the subset of examples translated to Rust which can be found in ./mex-examples. While this already validates the linking directives needed to link against libraries provided by Matlab it would be better if a bigger surface of the exposed C API could be tested to make sure the bindings work correctly and nothing is missing.

Workflow

1. Pick a C-example provided by Matlab in matlabroot/extern/examples/ that is missing
2. Make a new cdylib library crate in ./mex-examples with the name of the example (words should be separated by '-' for consistency) and matlab-sys as a path dependency
3. Translate the C-example you picked while staying close to the structure of the C-example
4. Add the exact name of the translated example package to TEST_EXAMPLES in file ./xtask/src/test.rs
5. Add at least one matlab unit test for the translated example to the file ./xtask/src/test.m. Follow the examples provided by the other tests or the documentation from Matlab.
6. Run the tests (cargo xtask test) to make sure everything works. If the new test fails validate your translation of the C-example and the test case you added to test.m. If both are correct open an issue describing the problem.