Expose alpha_code and codepoints patterns and improve name index

Aliases also needs to be indexed as "by name" so that :+1: works.

I've fixed gemojione indexes manually so that we don't have to filter out registered copyright and trademark unicode text representation that were wrongly being converted to the emoji version.

This allows us to remove additional custom code from GitLab and rely only on the gem.

See: https://gitlab.com/gitlab-org/gitlab/blob/3b8fac142dff2167d691382577cd0484a373f517/lib/banzai/filter/emoji_filter.rb#L55-70