Add basic bash and Python tasks (#10548)

Part of https://github.com/zed-industries/zed/issues/5141

* adds "run selection" and "run file" tasks for bash and Python.
* replaces newlines with `\n` symbols in the human-readable task labels
* properly escapes task command arguments when spawning the task in
terminal

Caveats:

* bash tasks will always use user's default shell to spawn the
selections, but they should rather respect the shebang line even if it's
not selected
* Python tasks will always use `python3` to spawn its tasks now, as
there's no proper mechanism in Zed to deal with different Python
executables

Release Notes:

- Added tasks for bash and Python to execute selections and open files
in terminal

crates/languages/src/bash.rs

@@ -0,0 +1,18 @@
+use language::ContextProviderWithTasks;
+use task::{TaskTemplate, TaskTemplates, VariableName};
+
+pub(super) fn bash_task_context() -> ContextProviderWithTasks {
+    ContextProviderWithTasks::new(TaskTemplates(vec![
+        TaskTemplate {
+            label: "execute selection".to_owned(),
+            command: VariableName::SelectedText.template_value(),
+            ignore_previously_resolved: true,
+            ..TaskTemplate::default()
+        },
+        TaskTemplate {
+            label: format!("run '{}'", VariableName::File.template_value()),
+            command: VariableName::File.template_value(),
+            ..TaskTemplate::default()
+        },
+    ]))
+}