Remove redundant `require`s from Banzai files

We're trying to avoid circular dependency errors.

lib/banzai/filter.rb

-require 'active_support/core_ext/string/output_safety'
-
 module Banzai
   module Filter
     def self.[](name)

lib/banzai/filter/autolink_filter.rb

-require 'html/pipeline/filter'
 require 'uri'
 
 module Banzai

lib/banzai/filter/emoji_filter.rb

-require 'action_controller'
-require 'gitlab_emoji'
-require 'html/pipeline/filter'
-
 module Banzai
   module Filter
     # HTML filter that replaces :emoji: with images.

lib/banzai/filter/external_link_filter.rb

-require 'html/pipeline/filter'
-
 module Banzai
   module Filter
     # HTML Filter to add a `rel="nofollow"` attribute to external links

lib/banzai/filter/gollum_tags_filter.rb

-require 'banzai'
-require 'html/pipeline/filter'
-
 module Banzai
   module Filter
     # HTML Filter for parsing Gollum's tags in HTML. It's only parses the

lib/banzai/filter/markdown_filter.rb

-require 'html/pipeline/filter'
-
 module Banzai
   module Filter
     class MarkdownFilter < HTML::Pipeline::TextFilter

lib/banzai/filter/milestone_reference_filter.rb

-require 'banzai'
-
 module Banzai
   module Filter
     # HTML filter that replaces milestone references with links.

lib/banzai/filter/redactor_filter.rb

-require 'html/pipeline/filter'
-
 module Banzai
   module Filter
     # HTML filter that removes references to records that the current user does

lib/banzai/filter/reference_filter.rb

-require 'active_support/core_ext/string/output_safety'
-require 'html/pipeline/filter'
-
 module Banzai
   module Filter
     # Base class for GitLab Flavored Markdown reference filters.

lib/banzai/filter/reference_gatherer_filter.rb

-require 'html/pipeline/filter'
-
 module Banzai
   module Filter
     # HTML filter that gathers all referenced records that the current user has

lib/banzai/filter/relative_link_filter.rb

-require 'html/pipeline/filter'
 require 'uri'
 
 module Banzai

lib/banzai/filter/sanitization_filter.rb

-require 'html/pipeline/filter'
-require 'html/pipeline/sanitization_filter'
-
 module Banzai
   module Filter
     # Sanitize HTML

lib/banzai/filter/syntax_highlight_filter.rb

-require 'html/pipeline/filter'
 require 'rouge/plugins/redcarpet'
 
 module Banzai

lib/banzai/filter/table_of_contents_filter.rb

-require 'html/pipeline/filter'
-
 module Banzai
   module Filter
     # HTML filter that adds an anchor child element to all Headers in a

lib/banzai/filter/upload_link_filter.rb

-require 'html/pipeline/filter'
 require 'uri'
 
 module Banzai

lib/banzai/filter/yaml_front_matter_filter.rb

-require 'html/pipeline/filter'
-require 'yaml'
-
 module Banzai
   module Filter
     class YamlFrontMatterFilter < HTML::Pipeline::Filter

lib/banzai/pipeline/base_pipeline.rb

-require 'html/pipeline'
-
 module Banzai
   module Pipeline
     class BasePipeline

lib/banzai/pipeline/wiki_pipeline.rb

-require 'banzai'
-
 module Banzai
   module Pipeline
     class WikiPipeline < FullPipeline