Fix missing button styles on some forms (#33771)

app/views/oauth/authorizations/new.html.haml

@@ -35,7 +35,8 @@
         = form.hidden_field :scope,
                             value: @pre_auth.scope
         = form.button t('doorkeeper.authorizations.buttons.authorize'),
-                      type: :submit
+                      type: :submit,
+                      class: 'btn'
 
       = form_with url: oauth_authorization_path, method: :delete do |form|
         = form.hidden_field :client_id,
@@ -52,4 +53,4 @@
                             value: @pre_auth.scope
         = form.button t('doorkeeper.authorizations.buttons.deny'),
                       type: :submit,
-                      class: 'negative'
+                      class: 'btn negative'

app/views/oauth/authorizations/show.html.haml

@@ -4,4 +4,4 @@
     .input-copy
       .input-copy__wrapper
         = copyable_input value: params[:code], class: 'oauth-code'
-      %button{ type: :button }= t('generic.copy')
+      %button.button{ type: :button }= t('generic.copy')