FMIL: Fix a few typos for #3241
FMIL: Remove state vrefs and internal flag `callEventUpdate` from FMI2 test fmus for #3241, since they are no longer needed
FMIL: Update to the event model of FMI2.0rc1 in me import test and test fmu, for #3241.
* Let `fmiNewDiscreteSates` in FMI2 test fmu do what `fmiEventUpdate` does, and make it safe for successive invocations. 
* Rewrite `fmi_import_me_test.c` to use the event model of FMI2.0rc1.
* Add missed `FMILIB_EXPORT` declarations.
FMIL: Remove functions `fmiEventUpdate` and `fmiCompletedEventIteration` for #3241.

Also
* Remove now unused variable `intermediateResults`.
* Make `fmi_do_step` in cs test fmu call `fmi_new_discrete_states` in place of `fmi_event_update`.
FMIL: Remove XML attributes `canHandleEvents` and `canSignalEvents` for cosimulation, for #3267.

Also remove commented-out code for removed attributes `providesPartiallDerivativesOf_XXX`.
FMIL: remove unused `intermediateResults` that was missed in r5548, for #3241
FMIL: Add <DefaultExperiment> attribute stepSize, for #3267