pulumi up --refactor: Making refactoring stacks easy

[iwahbe]

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Issue details

Renaming resources and moving them into and out of component resources is doable in pulumi with aliases, but it requires you to know how resource URNs work. Using aliases requires you to make multiple code edits to insert the aliases, run pulumi up --expect-no-changes and then manually remove the aliases.

We should add a new flag to pulumi up: --refactor. When pulumi up --refactor is run, pulumi runs the user program and tries to modify the existing state to match the new state suggested by the user's program.

Old resource state can be matched up with new resource requests via:

• Name
• Property set

Importantly, pulumi up --refactor would allow the creation and deletion of component resources, making it simple to move a resource (or a set of resources) into a component resource our out of a component resource.

To avoid ambiguity, --refactor prevents creates, updates and deletes of custom resources.

This is a possible implementation of #6078.

Affected area/feature