[MIG] web_m2x_options_manager: Migration to 15.0

- Fix postprocess inherit (removed from v15), and use _postprocess_tag_field
for create/edit options: In v14 it worked with inheriting the "postprocess"
method because in each recursive call it passed a section of the view, in the
way that it went through all the child nodes of the root node, and passed through
the fields, and now in v15 the method "_postprocess_view "it just does the while,
and we never go through the nodes.

- Fix pylint errors: xml-deprecated-tree-attributte, attribute-string-redundant,
translation-positional-used

web_m2x_options_manager/__manifest__.py

@@ -6,7 +6,7 @@
     "summary": 'Adds an interface to manage the "Create" and'
     ' "Create and Edit" options for specific models and'
     " fields.",
-    "version": "14.0.1.1.0",
+    "version": "15.0.1.0.0",
     "author": "Camptocamp, Odoo Community Association (OCA)",
     "license": "AGPL-3",
     "category": "Web",