Issue #2805205 by andrewmacpherson, michielnugter, lauriekap, BarisW, pk188, Ehud, arunkumark, SteffenR, Lendude, droplet, alexpott, xiwar: Provide screen-reader feedback when filtering by block name

Issue #1996238 by sun, nod_, damiankloip, Wim Leers, longwave, alexpott, Xano, mdrummond, Mark Carver, Jeff Burnz, highrockmedia, joelpittet, et al: Replace hook_library_info() by *.libraries.yml file.