Properly print leading comments and indentation in functions

Store the entire function declaration, not just its job list.
This allows us to extract the body of the function complete with any
leading comments and indents.

Fixes #5285

tests/checks/function-definition.fish

@@ -0,0 +1,35 @@
+#RUN: %fish %s
+
+function stuff --argument a b c
+    # This is a comment
+    echo stuff
+    # This is another comment
+end
+
+functions stuff
+#CHECK: # Defined in {{.*}}
+#CHECK: function stuff --argument a b c
+#CHECK:    # This is a comment
+#CHECK:    echo stuff
+#CHECK:    # This is another comment
+#CHECK: end
+
+function commenting
+
+    # line 2
+
+    # line 4
+
+    echo Bye bye says line 6
+end
+
+functions commenting
+#CHECK: # Defined in {{.*}}
+#CHECK: function commenting
+#CHECK:     
+#CHECK:     # line 2
+#CHECK:     
+#CHECK:     # line 4
+#CHECK:     
+#CHECK:     echo Bye bye says line 6
+#CHECK: end