Demo: transaction based installer plugin hooks

[soapy1]

An alternative way to structure the installer plugin hooks is to accept a list of packages and return a set of transactions for conda to execute. In this approach, the installer plugin is responsible for creating the custom transactions. And conda is responsible for executing them. So, the plugin is not responsible for making modifications to the filesystem.

An interface might look like:

def install(
  prefix: str, specs: Iterable[str], *args, **kwargs
) -> Action

The goal of this issue is to write a demo to try this approach to installer plugins. It would be good to start with 2 plugins:

• an identity plugin that is able to inject a simple action into the conda transaction system. This is a first step to prove that this approach is possible. If this is successful, create a follow up pip plugin
• a pip plugin that injects some actions for installing pip packages.

ref: https://docs.google.com/document/d/1ca1jvxV1a82wS-veU3WYwoP9fk6I7DljzjUSB2Y8yZ4/edit?pli=1&tab=t.0