This MR adds custom emoji banzai filter and is
used in GFM pipeline. It adds rspec for the filter.

Fix perl backrefs cop

Add changelog for the change

Add query recorder spec, multiple emoji

Apply suggestions to filter

Change method body for some filter functions

Use common regex from custom emoji model

Move regex to constant in emoji model

Revert regex changes

Add two same custom emoji test

Reuse part of regex in banzai filter

Use filter in appropriate places

Fix pipeline spec failures

Check fallbackEmoji before setting fallback

RUn yarn prettier

Apply suggestions and add new regex

Escape hypen for regex to fix rubocop warning

Use custom emoji filter only in GFM pipeline

Use single quotes for regex

Use regexp object and move hyphen to end

Use regexp object

Use regexp object

Use freeze for regexp object