feat(#505): enable default multi-arch build

[nohant]

this is done as a basic configuration for #505
the build is correctly working on my host but i dont know how to test it more :(

the part of the github action i think should be discussed or at least taken care of by someone more expert than me

[github-actions]

@nohant Image is available for testing. docker pull stakater/ingressmonitorcontroller:SNAPSHOT-PR-526-a3c36478

[bnallapeta]

@nohant
Instead of having different tags for different platforms for the images, it is easier on the user to just have the same tag and let docker figure out the platform.
If you take a look at our Reloader images, we have done this already by having the same tag with multi-platform support.
Could you please follow the same standard here too? The changes here look mostly right except the Docker push step. You can refer to this one for reference.

[nohant]

@bnallapeta you are right im sorry, im too used to how we do that.
Now it should work the same as you said in the other configurations.

[bnallapeta]

@nohant Its still not generating multi arch images. I am checking on this. Will get back to you.

[nohant]

@bnallapeta don't worry mate, I'm sure i've forgot something :D
thanks for the help, really appreciate.

[nohant]

fixed all the request points, sorry for the matrix leftover.

[bnallapeta]

@nohant We now have multi arch support for IMC. Thank you :)

https://hub.docker.com/layers/stakater/ingressmonitorcontroller/v2.1.39/images/sha256-f9347ced1826bc88f83ca4091499c706d25188e6b17db80bd697f4fc5d7ff706?context=explore