Migrate Sortable.js to NPM provided version of Sortable
Summary
Sortable.js currently in use in several places like Issue Boards is static and is served from vendor/assets/javascripts
and is currently at version 1.4.2
, while the latest library version published on NPM is 1.7.0 (at the time of opening this issue).
Proposal
We can easily move the library from vendor
to npm provided version to ensure that it always stays up to date and we can take advantage of Webpack's tree-shaking to load the package only on pages where it is being used.