Add Python venv activation support for Windows and PowerShell (#17839)

Release Notes:

- Add Python venv activation support for Windows and PowerShell

Additional:

I discovered a related bug on my Windows system. When first opening the
project, it fails to detect the virtual environment folder `.venv`.
After expanding the .venv folder in the Project Panel, it then becomes
able to detect the virtual environment folder. However, I don't know how
to fix it.

crates/terminal/src/terminal_settings.rs

@@ -87,6 +87,7 @@ pub enum ActivateScript {
     Csh,
     Fish,
     Nushell,
+    PowerShell,
 }
 
 #[derive(Clone, Debug, Default, Serialize, Deserialize, JsonSchema)]