Support preCICE Exception system

[BenjaminRodenberg]

In precice/precice#1594 we are currently introducing an exception system for preCICE. We should also support this in the python bindings.

Some necessary steps that I see here:

• Cython has some support for C++ Exception, but we need to explicitly state that certain functions may throw an exception. For details see https://cython.readthedocs.io/en/latest/src/userguide/wrapping_CPlusPlus.html#exceptions.
• Start with a single base exception precice.Error
• Define our own exception system for more fine-grained errors (basically map thrown C++ preCICE exceptions to python exceptions). We should use larger python Frameworks as a template here (numpy, for example, also defines its own exceptions)
• We should also make sure to be able to catch unknown exceptions (imagine C++ preCICE introduces a FooError upstream, then we want to at least raise a generic precice.Error here until we implement precice.FooError)
• We should also add (some) tests for error handling. I think we can simply extend our mocked version of preCICE with some dummy exceptions and explicitly test for them to make sure that passing the error generally works.

[BenjaminRodenberg]

As soon as precice/precice#2065 is merged we should be able to start working on this issue.