Submodules w/ beta Istio and CloudRun addons

[ocervell]

This PR adds two new submodules:

• beta-public-cluster: Creates a public GKE cluster with beta features enabled.
• beta-private-cluster: Creates a private GKE cluster with beta features enabled.

This PR supports Istio and CloudRun GKE addons beta features. Other PRs are planned to add support for all other beta features.

TODO:

• Example for beta-public-cluster
• Example for beta-private-cluster

[ocervell]

Fixes #107

[thefirstofthe300]

Any update on this PR? I am in need of application secrets encryption so I'd like to base a PR to add this feature off this PR if this is the route we're going.

[morgante]

@ocervell Can you rebase on master?

[aaron-lane]

Please rebase against master.

[chrislovecnm]

Is support for this possible without these changes? We have VPA and binary auth now as well. Also istion will soon have configurations to pass in.

[morgante]

@chrislovecnm We will either need to merge this PR or a separate one to support these new optional addons.

@ocervell Are you able to pick this up or should we hand it off?

[ocervell]

@aaron-lane @morgante rebased against master

[ocervell]

@chrislovecnm we'll merge this and add support for VPA and binary auth, Istio config in a further PR (feel free to attack it :))

[chrislovecnm]

Woop!

[dmyerscough]

Any ideas when this will be merged in?

[morgante]

Approving this as a start.

Remaining tasks:

• Integrate Istio and other submodules
• Remove all beta features from main module - Ensure that GA modules don't depend on beta functionality #181
• Add testing for beta module - Add tests for beta submodules/examples #180