Issue #3079738 by lauriii, saschaeggi, webchick, xjm, andrewmacpherson,...

Issue #3079738 by lauriii, saschaeggi, webchick, xjm, andrewmacpherson, shimpy, effulgentsia, Wim Leers, DyanneNova, svettes, rainbreaw, fhaeberle, ckrina, AaronMcHale, justafish, catch, charlieweb82, AntoineH, lot007, pzajacz, kostyashupenko, jasonbarrie, antonellasevero, finnsky, worldlinemine, bnjmnm, RobLoach, Dennis Cohn, huzooka, Archita Arora, joachim, jrockowitz, benjifisher, shaal, Gábor Hojtsy, quiron, L2G2, ccasals, hampercm, if-jds, abhisekmazumdar, Kami Amiga, pivica, zrpnr, BrightBold, imalabya, jhedstrom, Neslee Canil Pinto, maliknaik, junaidmasoodi, Maithri Shetty, pranav73, mandclu, modulist, nod_, philosurfer, phenaproxima, mherchel, mlncn, rafuel92, leymannx, kiboman, Swapnil_Kotwal, anevins, evankay, rfmarcelino, thamas, brianperry, idebr, joelpittet, boulaffasae, alexpott, volkerk, DuneBL, Eli-T, Mahenkvyas22: Add Claro administration theme to core

(cherry picked from commit 1786bc19)