Finalize release flow for Toolbox architecture

[Kira-Pilot]

NOTE: JetBrains has not yet communicated a release timeline or strategy. This ticket should be picked up after that piece of the puzzle has been solved.

We should implement a release flow that allows us to share existing code. This may look like adding another branch on which we enable CI, so we have distinct branches for the old Gateway and the new. If we use this approach, we should be mindful that existing Gateway actually already has two branches - eap (early access program) and main. The newer Gateway flavor may require two branches, too.

Documentation and deprecation consideration should also be considered as part of this ticket.

• Implement release flow that is tied in with our existing CI pipeline and considers a 2-branch approach for Toolbox (early access and stable)
• Understand and plan around the deprecation of the existing Gateway, which JetBrains has communicated may happen by EOY UPDATE 9/30/2024 - Gateway should not be deprecated for another year or so.
• Document the new Gateway architecture and also plan proactive messaging for old Gateway users so they understand the deprecation timeline and any feature limitations or performance differences identified during the completion of this milestone (product to help out here)