Incorporate API and Behavior feedback on the environment manager extension

[karthiknadig]

APIs for python environment:

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1. API for create/remove environments provider
2. API for environment discovery, collection, and change
3. API for selection and selection change
4. API for package list and package list change
5. API for package install/remove
6. API to add/remove folders or scripts with custom environments
7. API to identify a given path to an environment
8. API for Shell specific activation commands
9. API for custom arguments to Install/Remove packages
10. API for custom arguments to create/remove environments

Environment management behavior:

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1. Show environment for the selected item in the status bar
2. Show button to add folder in file explorer
3. Show button to select environment in the file explorer view (on python binaries and on environment folders)
4. shell specific activation commands
5. clear cache command
6. Remove package manager selection while selecting env manager
7. Only selected env manager is initialized
8. File system watcher for envs.

Env Manager Contributions:

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1. Use pet to provide data for environments
2. Selection Caching
3. Conda env manager (demo support)
4. System (built in)
5. venv (built in)
6. Uv (if available)

Package Manager Contributions:

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1. pip (built in)
2. conda (demo support)
3. uv (if available built-in)