External Libraries: Update Masonry to 4.2.2 and imagesLoaded to 4.1.4.

Notable changes include dropping support for IE 8 & 9, which are no longer supported by WordPress core either.

Release notes:
https://github.com/desandro/masonry/releases
https://github.com/desandro/imagesloaded/releases

Changelogs:
https://github.com/desandro/masonry/compare/v3.3.2...v4.2.2
https://github.com/desandro/imagesloaded/compare/v3.2.0...v4.1.4

Props pierlo, hareesh-pillai, grapplerulrich, pderksen, desrosj, garrett-eclipse, SergeyBiryukov.
Fixes #37675, #48031.
Built from https://develop.svn.wordpress.org/trunk@48038


git-svn-id: https://core.svn.wordpress.org/trunk@47805 1a063a9b-81f0-0310-95a4-ce76da25c4cd