nu: Add job control shortcuts

Using <c-z> when a process is running backgrounds it (default behavior)
using the new nushell job control system (since v0.103).
This change also lets you re-foreground the backgrounded program with
the same <c-z> key mapping.

Additionally we add the `fg` alias which does the same and thus mimics
the fg command of other shells like zsh.

terminal/.config/nushell/config.nu

@@ -119,6 +119,17 @@ $env.config.keybindings = [
             "
         }
     }
+    # job control
+    {
+        name: unfreeze_job
+        modifier: control
+        keycode: char_z
+        mode: ["emacs", "vi_normal", "vi_insert"]
+        event: {
+            send: executehostcommand
+            cmd: "job unfreeze"
+        }
+    }
 ]
 
 alias l = ls
@@ -131,3 +142,6 @@ def --env mcd [path: path] {
 }
 
 alias v = nvim
+
+# requires minimum nushell: 0.103 for job control
+alias fg = job unfreeze