Move various "examples" into snippets. Several examples that were less
than a full mechanism or robot were moved to snippets. `arcadedrive` and
`tankdrive` were removed in favor of their Gamepad variants. `hidrumble`
was removed due to being too simple. `potentiometerpid` was removed
because of low utility. `gyromecanum` replaced `mecanumdrive` for
deduplication and because very few teams run holonomic drivetrains
without gyros.
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.
