Fuzzing: Initial commit

[AdamKorcz]

Adds initial fuzzing set up for helm-controller.

To build and run:

git clone https://github.com/AdamKorcz/helm-controller --branch fuzz1
cd helm-controller/fuzz
sudo docker build . --tag flux-fuzzing-image

To run either of the fuzzers, uncomment the last line in the Dockerfile and build the image again.

[stefanprodan]

Superseded by #396