erp5_web_renderjs_ui: make translation gadget generic

- add uritemplate
- add getTranslationDict method to retrieve a language dictionary from ERP5
- add fetchLanguage to handle browser working with "en-EN" vs gadget/ERP5 only using "en"
- add ready handler to retrieve languages from web_site_module and translation method from custom
initialization gadget (temp fix) to remove hardcoded configuration parameters
- add error handler to catch missing translation method and not translate/expose language options to
ensure compat with existing rJS web sites
- add ready handler to initialize plugin and re-render header once translations are available
- add method to expose available languages, so they can be fetched from the panel gadget
- fix translation methods to only work with strings being passed in and out

bt5/erp5_web_renderjs_ui/PathTemplateItem/web_page_module/rjs_gadget_translate_html.xml

@@ -115,6 +115,7 @@
     <script src="RSVP.js"></script>\n
     <script src="renderjs.js"></script>\n
     <script src="i18next.js"></script>\n
+    <script src="uritemplate.js"></script>\n
 \n
     <!-- custom script -->\n
     <script src="gadget_translate.js"></script>\n
@@ -258,7 +259,7 @@
             </item>
             <item>
                 <key> <string>serial</string> </key>
-                <value> <string>939.45272.15892.529</string> </value>
+                <value> <string>939.45272.47644.64085</string> </value>
             </item>
             <item>
                 <key> <string>state</string> </key>
@@ -276,7 +277,7 @@
                     </tuple>
                     <state>
                       <tuple>
-                        <float>1418892983.83</float>
+                        <float>1419953317.85</float>
                         <string>GMT</string>
                       </tuple>
                     </state>