Properly pass nested script arguments for tasks (#10776)

Closes
https://github.com/zed-industries/zed/discussions/10732#discussion-6524347
introduced by https://github.com/zed-industries/zed/pull/10548 while
keeping both Python and Bash run selection capabilities.

Also replaced redundant `SpawnTask` struct with `SpawnInTerminal` that
has identical fields.

Release Notes:

- Fixed incorrect task escaping of nested script arguments

---------

Co-authored-by: Piotr Osiewicz <piotr@zed.dev>

crates/languages/src/python.rs

@@ -186,13 +186,7 @@ pub(super) fn python_task_context() -> ContextProviderWithTasks {
         TaskTemplate {
             label: "execute selection".to_owned(),
             command: "python3".to_owned(),
-            args: vec![
-                "-c".to_owned(),
-                format!(
-                    "exec(r'''{}''')",
-                    VariableName::SelectedText.template_value()
-                ),
-            ],
+            args: vec!["-c".to_owned(), VariableName::SelectedText.template_value()],
             ignore_previously_resolved: true,
             ..TaskTemplate::default()
         },