Override Action View name inference in settings/keyword_mutes.

Glitch::KeywordMute's name is inferred as glitch_keyword_mutes, and in
templates this turns into e.g. settings/glitch/keyword_mutes.  Going
along with this convention means a lot of file movement, though, and for
a UI that's as temporary and awkward as this one I think it's less
effort to slap a bunch of as: options everywhere.

We'll do the Right Thing when we build out the API and frontend UI.

app/views/settings/keyword_mutes/edit.html.haml

 - content_for :page_title do
   = t('keyword_mutes.edit_keyword')
 
-= simple_form_for @keyword_mute, url: settings_keyword_mute_path(@keyword_mute) do |f|
+= simple_form_for @keyword_mute, url: settings_keyword_mute_path(@keyword_mute), as: :keyword_mute do |f|
   = render 'shared/error_messages', object: @keyword_mute
   = render 'fields', f: f

app/views/settings/keyword_mutes/index.html.haml

@@ -10,7 +10,7 @@
         %th
         %th
       %tbody
-        = render @keyword_mutes
+        = render partial: 'keyword_mute', collection: @keyword_mutes, as: :keyword_mute
 
 = paginate @keyword_mutes
 .simple_form

app/views/settings/keyword_mutes/new.html.haml

 - content_for :page_title do
   = t('keyword_mutes.add_keyword')
 
-= simple_form_for @keyword_mute, url: settings_keyword_mutes_path do |f|
+= simple_form_for @keyword_mute, url: settings_keyword_mutes_path, as: :keyword_mute do |f|
   = render 'shared/error_messages', object: @keyword_mute
   = render 'fields', f: f