Replace proto_tree_add_text in non-generated files

As requested by Michael Mann, most of the occurences of proto_tree_add_text/proto_item_add_subtree are replaced with proto_tree_add_subtree(_format) or proto_tree_add_item/proto_item_append_text in the non-generated files.

Change-Id: I27cccde88780adef43c78efd26333f47af098ad6
Reviewed-on: https://code.wireshark.org/review/4726
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>