Enable File Type template data lang selection

Give HbFileType the correct marker interface (TemplateLanguageFileType)
to enable selecting a global template data language for each file
extension in "Settings->File Types->Handlebars/Mustache".  This
also enabled the "Change template data lang to..." quick fix
for errors in templates
Enable the "Change Template Data Language" action

Give HbFileViewProvider the correct marker interface
(ConfigurableTemplateLanguageFileViewProvider) to enable the "File->
Change Template Data Language" action for our templates