Using MrcLib on the robot is going to be the plan for the future, to
make things easier.
MrcLib is how sim is supported going forward. The desktop version of
mrclib can act as a robot server.
This is set up where the mrclib interface is in shared code. On robot,
that is the only backend used. On desktop, a default sim backend is
used. However, the sim plugin can switch that to the real robot backend,
so the robot code will exactly look like a real robot.
The initial build file generation for robotpy projects was relatively
naive and purpose built to get `allwpilib` compiling, without supporting
all the available features.
This modifies the generation scripts to be able to support multiple
embedded libraries, which will be necessary for #8858, since `mrclib.so`
will need to be bundled along with the hal libraries. In addition some
cleanup was done to get the wheels looking more like what is in pypi.
This hooks up the bazel build to the robotpyExamples. It can use the
(formly pyfrc or whatever) automatic unit tests for an example, as well
as exposing the ability to run the example in simulation, with or
without `halsim_gui` with a command such as `bazel run
//robotpyExamples:AddressableLED-sim`
This required building and using wheels instead of just a normal
`py_library`, so that things like `ENTRY_POINTS` can be used. I took a
bare bones approach to building and naming the wheels (for example the
native ones don't have the OS info or python version in them, so they
wouldn't be suitable publish to pypi, but that can always be updated
later.
