Allow discovery of venv in VIRTUAL_ENV env variable (#16853)

## Summary

Fixes #16744 

Allows the cli to find a virtual environment from the VIRTUAL_ENV
environment variable if no `--python` is set

## Test Plan

Manual testing, of:
- Virtual environments explicitly activated using `source .venv/bin/activate`
- Virtual environments implicilty activated via `uv run`
- Broken virtual environments with no `pyvenv.cfg` file

crates/red_knot_python_semantic/src/module_resolver/resolver.rs

@@ -223,14 +223,15 @@ impl SearchPaths {
         static_paths.push(stdlib_path);
 
         let site_packages_paths = match python_path {
-            PythonPath::SysPrefix(sys_prefix) => {
+            PythonPath::SysPrefix(sys_prefix, origin) => {
                 // TODO: We may want to warn here if the venv's python version is older
                 //  than the one resolved in the program settings because it indicates
                 //  that the `target-version` is incorrectly configured or that the
                 //  venv is out of date.
-                VirtualEnvironment::new(sys_prefix, system)
+                VirtualEnvironment::new(sys_prefix, *origin, system)
                     .and_then(|venv| venv.site_packages_directories(system))?
             }
+
             PythonPath::KnownSitePackages(paths) => paths
                 .iter()
                 .map(|path| canonicalize(path, system))