See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3566

https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2912/

This reverts merge request !15009

Reduced the technical debt around our JS flash function by making it a
module that is imported rather than relying on the global function.
The global function still exists mainly for technical debt with how
some requests are being completed, but new JS should import the module
directly.

Also reduces some tech debt in the file by removing the need for jQuery.
Instead Flash is now 100% vanilla JS.

Removes set favicon related methods from global scope
Improves test related with favicon

Removes convertPermissionToBoolean from global scope.
Adds tests for convertPermissionToBoolean - were non existant

Removes setParamInURL from gl.utils

Removes parseIntPagination from gl.utils namespace

Remove normalizeCRLFHeaders from gl.utils namespace

Removes normalizeHeaders from gl.utils namespace

Use gl.utils for filtered search

Fix bad import

Fix broken test by cleaning window.history namespace

Adds changelog