uploads: allow changing thumbnail size on My Uploads / All Uploads pages.

* Add a "Size" menu to the My Uploads / All Uploads pages to allow
  changing the thumbnail size.
* Make the My Uploads / All Uploads pages use the same thumbnail size as
  the post index page.
* Change the "Gallery | Table" links on the My Uploads page to icons.

app/controllers/media_assets_controller.rb

@@ -5,6 +5,8 @@ class MediaAssetsController < ApplicationController
 
   def index
     @limit = params.fetch(:limit, CurrentUser.user.per_page).to_i.clamp(0, PostSets::Post::MAX_PER_PAGE)
+    @preview_size = params[:size].presence || cookies[:post_preview_size].presence || MediaAssetGalleryComponent::DEFAULT_SIZE
+
     @media_assets = authorize MediaAsset.visible(CurrentUser.user).paginated_search(params, limit: @limit, count_pages: false)
     @media_assets = @media_assets.includes(:media_metadata, :post)
     respond_with(@media_assets)