Support duplication of an environment

[ankit-ls]

Summary

We have a usecase where we want to duplicate an environment with all the apps contained in it, with few simple clicks.

Proposal

We can provide an option in the Global Configs to duplicate an environment.

• It can be a simple form on the UI, asking user to select one of the existing environments.
• On selecting an env, Devtron should list all the apps currently using that env.
• User can select all apps or a selected few for their new environment.
• Once the user clicks on Duplicate button, all the apps selected should have a CD pipeline created pointing to new env.
• Every app should also have the same Override configs for the new environment, as was in the original environment.
• Once Duplicated, we can also optionally give a Deploy All button on the UI to deploy all the newly created CD pipelines.

AB#416