acp_thread: Respect terminal settings shell for terminal tool environment (#39349)

When sourcing the project environment for the terminal tool, we will now
do so by spawning the shell specified by the users `terminal.shell`
setting (or as usual fall back to the login shell).

Closes #37687 

Release Notes:

- N/A

crates/languages/src/python.rs

@@ -1187,11 +1187,13 @@ impl ToolchainLister for PythonToolchainProvider {
                         ShellKind::PowerShell => ".",
                         ShellKind::Fish => "source",
                         ShellKind::Csh => "source",
-                        ShellKind::Posix => "source",
+                        ShellKind::Tcsh => "source",
+                        ShellKind::Posix | ShellKind::Rc => "source",
                     };
                     let activate_script_name = match shell {
-                        ShellKind::Posix => "activate",
+                        ShellKind::Posix | ShellKind::Rc => "activate",
                         ShellKind::Csh => "activate.csh",
+                        ShellKind::Tcsh => "activate.csh",
                         ShellKind::Fish => "activate.fish",
                         ShellKind::Nushell => "activate.nu",
                         ShellKind::PowerShell => "activate.ps1",
@@ -1220,7 +1222,9 @@ impl ToolchainLister for PythonToolchainProvider {
                     ShellKind::Nushell => Some(format!("\"{pyenv}\" shell - nu {version}")),
                     ShellKind::PowerShell => None,
                     ShellKind::Csh => None,
+                    ShellKind::Tcsh => None,
                     ShellKind::Cmd => None,
+                    ShellKind::Rc => None,
                 })
             }
             _ => {}