Standardize make tooling. Remove unnecessary duplication where possible,
including with common copies of go fmt/vet/test targets.

Slighty shift around controller and sidecar 'cmd/' directories to allow
specifying a template Dockerfile that can be used to generate
Dockerfiles for each image easily.

Where it makes sense, this work adopts the make target naming and
Dockerfile usage of the kubebuilder project. The biggest divergence from
that template is because we build 2 images from one repo, and because we
have a 'proto/' dir for gRPC code.

Significant testing was done to ensure that the tooling works with Unix
make on MacOS as well as GNU-Make (gmake). Testing was also done to
ensure the `make all` target works well with `make -j`'s parallel
execution flag, allowing dev speedup where possible.

Some proto targets were adjusted to allow make to do a better job
detecting when file/code generation is not necessary, saving time in the
common case where there are no proto changes.

A future goal, which this helps lay groundwork for, will be to make sure
that there are top-level make targets that are usable by Prow CI. For
example, 'test' can be used to run all unit tests. Any unit tests added
to any component can be included in 'make test' to ensure we don't need
to make frequent changes to Prow CI definitions. Similarly 'make build'
should build all binaries and images to ensure builds work. 'make
generate' and 'make codegen' should include targets that generate files
in any way, which will allow Prow CI to ensure developers are running
all generators. In the future, we have room to add intall and/or e2e
tests as make targets.

Signed-off-by: Blaine Gardner <[email protected]>