Adding pipenv support

[eleanorjboyd]

fixes #686

[Copilot]

Pull Request Overview

This PR adds comprehensive support for Pipenv virtual environment management to the Python environments extension. It introduces functionality to discover, manage, and resolve Pipenv environments similar to existing support for Conda, Poetry, and Pyenv.

• Implements complete Pipenv environment discovery and management through a new PipenvManager class
• Adds utility functions for Pipenv path resolution, caching, and workspace/global environment persistence
• Integrates Pipenv support into the main extension activation flow

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/managers/pipenv/pipenvUtils.ts	Core utility functions for Pipenv path discovery, environment conversion, and persistence management
src/managers/pipenv/pipenvManager.ts	Main PipenvManager class implementing the EnvironmentManager interface for full Pipenv support
src/managers/pipenv/main.ts	Registration function to initialize Pipenv features and integrate with the extension
src/extension.ts	Extension activation updates to register Pipenv features alongside other environment managers
src/common/localize.ts	Localized strings for Pipenv-related UI messages

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[eleanorjboyd]

@cwebster-99 what documentation do I need to update alongside this?

[cwebster-99]

@eleanorjboyd the README.md is our current source of truth. It doesn't look to be updated to include any of the basic support manager (poetry, pipenv, pyenv). We can make a pass at updating the table in the Features section. Let me know if you would want to do that in this PR or I can create a separate one!

[eleanorjboyd]

ill create a separate PR but can add it