Create Docker image

[alegrey91]

harpoon needs a Dockerfile to build its own image.
This is part of the process to integrate harpoon in other repositories that make use of docker images when running tests.

Suppose to have a Kubernetes operator that runs e2e tests within a cluster.
This will first install the container image (through helm or other methods) on the cluster and then will run tests against the Kubernetes instance.
In order to integrate harpoon in this process, I was thinking to create our own docker image, so that everyone that wants to use harpoon in his e2e test suite, can add the harpoon image as final stage in his Dockerfile like so:

FROM golang:1.23 AS build
WORKDIR /src
COPY <<EOF /src/main.go
package main

import "fmt"

func main() {
  fmt.Println("hello, world")
}
EOF
RUN go build -o /bin/hello ./main.go

FROM harpoon:latest
COPY --from=build /bin/hello /bin/hello
CMD ["/bin/harpoon", "capture", "-f", "main.main", "--save", "--directory", "results/", "--", "./hello"]

This issue includes also the need of a pipeline to build the image and push it on a registry (dockerhub, quay.io).