windows: Detect when python3 is not usable and notify the user (#40070)

Fixes #39998

Debugpy and pylsp are installed in a Zed-global venv with pip. We need a
Python interpreter to create this venv when it doesn't exist and one of
these tools needs to be installed, and sometimes we attempt to use
`python3` from `$PATH`. This can cause issues on Windows, where out of
the box `python3` is a sort of shim that opens the Microsoft Store app.

This PR changes the debugpy installation path to create the Zed-global
venv using the Python interpreter from a venv in the project, and only
use python3 from `$PATH` if that fails. That matches how pylsp
installation already works. It also tightens up how we search for a
global Python installation by doing a basic sanity check (`python3 -c
'print(1 + 2)`) before accepting it, which should catch the Windows
shim.

Release Notes:

- windows: improved the behavior of Zed in situations where no global
Python installation exists.

crates/debugger_ui/src/debugger_panel.rs

@@ -268,12 +268,12 @@ impl DebugPanel {
 
             async move |_, cx| {
                 if let Err(error) = task.await {
-                    log::error!("{error}");
+                    log::error!("{error:#}");
                     session
                         .update(cx, |session, cx| {
                             session
                                 .console_output(cx)
-                                .unbounded_send(format!("error: {}", error))
+                                .unbounded_send(format!("error: {:#}", error))
                                 .ok();
                             session.shutdown(cx)
                         })?