vim-patch:8.2.{1536,1540}: charclass() (#19748)

vim-patch:8.2.1536: cannot get the class of a character; emoji widths are wrong

Problem:    Cannot get the class of a character; emoji widths are wrong in
            some environments.
Solution:   Add charclass(). Update some emoji widths.  Add script to check
            emoji widths.
4e4473c927

Use latest charclass() docs from Vim.
Rewrite DoIt() in emoji_list.vim in Lua.
Omit emoji table updates:
- emoji_width update looks wrong as these added ranges are only double-width when followed by 0xFE0F.
- Other updates are too old.

vim-patch:8.2.1540: the user cannot try out emoji character widths

Problem:    The user cannot try out emoji character widths.
Solution:   Move the emoji script to the runtime/tools directory.
98945560c1

src/nvim/eval.lua

@@ -72,6 +72,7 @@ return {
     chanclose={args={1, 2}},
     chansend={args=2},
     char2nr={args={1, 2}, base=1},
+    charclass={args=1, base=1},
     charcol={args=1, base=1},
     charidx={args={2, 3}, base=1},
     chdir={args=1, base=1},