Show random live subcategories and tags on homepage

[MemoryLeakDeath]

Description

To help surface more live streams on the homepage and introduce users to the category search function, I've added a tag cloud on the homepage. The cloud will be a random mix of both subcategories and tags taken from currently live channels across the platform regardless of time streamed.

Clicking a tag will automatically take the user to the appropriate category search page with the subcategory or tag already selected in the filter at the top of the page:

Limitations

• A maximum of 20 subcategories/tags will show on the homepage.
• Despite my best efforts, the database query tends to favor some categories over others when it comes to removing duplicate tags. For example, having two live streams -- one in the Art category and one in the Gaming category -- that both use the "Community Pride" tag will predominately surface one category over the other thus showing only one of the streams. This could be solved by having a more generic tag search that spans across categories.

[clone1018]

With the beta redesign, this PR will not be needed in its current form. Thank you for proposing the idea!