Add language toolchains (#19576)

This PR adds support for selecting toolchains for a given language (e.g.
Rust toolchains or Python virtual environments) with support for SSH
projects provided out of the box. For Python we piggy-back off of
[PET](https://github.com/microsoft/python-environment-tools), a library
maintained by Microsoft.
Closes #16421
Closes #7646

Release Notes:

- Added toolchain selector to the status bar (with initial support for
Python virtual environments)

.github/workflows/ci.yml

@@ -192,6 +192,9 @@ jobs:
     if: github.repository_owner == 'zed-industries'
     runs-on: hosted-windows-1
     steps:
+      # more info here:- https://github.com/rust-lang/cargo/issues/13020
+      - name: Enable longer pathnames for git
+        run: git config --system core.longpaths true
       - name: Checkout repo
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
         with: