Support Unicode version 15.1

Support Unicode version 15.1

* admin/unidata/BidiBrackets.txt:
* admin/unidata/BidiMirroring.txt:
* admin/unidata/Blocks.txt:
* admin/unidata/IdnaMappingTable.txt:
* admin/unidata/NormalizationTest.txt:
* admin/unidata/PropertyValueAliases.txt:
* admin/unidata/ScriptExtensions.txt:
* admin/unidata/Scripts.txt:
* admin/unidata/SpecialCasing.txt:
* admin/unidata/UnicodeData.txt:
* admin/unidata/confusables.txt:
* admin/unidata/copyright.html:
* test/manual/BidiCharacterTest.txt:
* admin/unidata/emoji-data.txt:
* admin/unidata/emoji-sequences.txt:
* admin/unidata/emoji-test.txt:
* admin/unidata/emoji-variation-sequences.txt:
* admin/unidata/emoji-zwj-sequences.txt: Update from Unicode data
files.
* admin/notes/unicode: Update instructions.
* lisp/international/characters.el: Update 'char-width-table'
data.
* etc/NEWS: Announce support for Unicode 15.1.