Add DNS endpoint support for GKE Hooks and Operators

[Merve40]

Description

Current GKE Hook only supports IP based endpoints for accessing control plane of GKE, they should now also support access using DNS endpoint.

Use case/motivation

A Cloud Composer environment that is in a separate VPC network than the GKE in question, cannot be accessed via internal IP endoints.
Enabling external IPs is not desired and setting up a bastion host is also not required anymore since access via DNS is now possible.

Related issues

No response

Are you willing to submit a PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[boring-cyborg]

Thanks for opening your first issue here! Be sure to follow the issue template! If you are willing to raise PR to address this issue please do so, no need to wait for approval.

[potiuk]

cc: @VladaZakharova -> wdyt?

[VladaZakharova]

Thanks for raising this issue, we are working right now on implementation

[jroachgolf84]

@VladaZakharova, are we all set to close out this issue?

[VladaZakharova]

Hi! yes, thank you :)