Replace Bamboo SCDF samples build w/ GitHub actions

[onobc]

Points of interest:

1. the push to Harbor registry will not work w/ public Github runners as we have to be on the VMware network
2. the stream-standalone-sample have been modified to output the kafka and rabbit variants

Possible improvements (TODO)

• remove version number from docker image inputs (will wait to do this in the clean-up of SCDF ticket where we bump version numbers)
• split the action.yml into 3 (build, publish, push)

Resolves gh-155

cc: @dturanski @sobychacko

[onobc]

So... what are we doing for copyrights in our GH action files?

[jvalkeal]

Versions for images could come from a pom file so that we don't need to modify workflows to change it. But that's minor thing and doesn't need to get done with this PR. I'd just merge this. Thx!

[onobc]

Versions for images could come from a pom file so that we don't need to modify workflows to change it. But that's minor thing and doesn't need to get done with this PR. I'd just merge this. Thx!

Yep, the hardcoded aspect of the versions is toil to keep up-to-date. This is in parity w/ the old Bamboo plan and I plan on making this better in the scope of #156 (which I will follow on w/ shortly after this).