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.
https://github.com/vim/vim/commit/4e4473c927167fd24e5c8df90e0e8035080cf2da

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.
https://github.com/vim/vim/commit/98945560c1ae6e2ddee820a7de718a36e3f4b6e5

Problem:    It is not possible to specify cell widths of characters.
Solution:   Add setcellwidths().
https://github.com/vim/vim/commit/08aac3c6192f0103cb87e280270a32b50e653be1

Co-Authored-By: delphinus <me@delphinus.dev>

Problem:    Menu functionality insufficiently tested.
Solution:   Add tests.  Add menu_info(). (Yegappan Lakshmanan, closes vim/vim#5760)
https://github.com/vim/vim/commit/0eabd4dc8ff50658f0ea0e92c7918a42242f6b80

Omit feedkeys() change: even if "L" flag is implemented it will likely
use input_enqueue(), which already checks for interrupts.

Omit Test_mouse_popup_menu(): already tested in Lua.

Problem:    Cannot easily restore a mapping.
Solution:   Add mapset().
https://github.com/vim/vim/commit/4c9243f9fb708c9010867d3cc8e928f36b58509a

Use MapArgument to reduce number of arguments of map_add().

N/A patches for version.c:

vim-patch:8.2.0809: build failure with small features

Problem:    Build failure with small features. (Tony Mechelynck)
Solution:   Move "expr" inside #ifdef.
https://github.com/vim/vim/commit/5a80f8ad5dc0b2cc63400255dcf3c63f6c1a2ef9

This change adds the necessary plumbing to annotate functions in funcs.c
as being allowed in run in luv fast events.

vim-patch:8.2.4903: cannot get the current cmdline completion type and position

Problem:    Cannot get the current cmdline completion type and position.
Solution:   Add getcmdcompltype() and getcmdscreenpos(). (Shougo Matsushita,
            closes vim/vim#10344)
https://github.com/vim/vim/commit/79d599b8772022af1d657f368c2fc97aa342c0da

vim-patch:8.2.4910: imperfect coding

Problem:    Imperfect coding.
Solution:   Make code nicer.
https://github.com/vim/vim/commit/9ff7d717aa3176de5c61de340deb93f41c7780fc

Problem:    New digraph functions use old naming scheme.
Solution:   Use the digraph_ prefix. (Hirohito Higashi, closes vim/vim#8580)
https://github.com/vim/vim/commit/29b857150c111a455f1a38a8f748243524f692e1

Problem:    Cannot add a digraph with a leading space.  It is not easy to list
            existing digraphs.
Solution:   Add setdigraph(), setdigraphlist(), getdigraph() and
            getdigraphlist(). (closes vim/vim#8580)
https://github.com/vim/vim/commit/6106504e9edc8500131f7a36e59bc146f90180fa

Use GA_APPEND_VIA_PTR in registerdigraph().
Use tv_list_append_*() in getdigraphlist_appendpair().
Put the error messages in digraph.c.
E196 is N/A.
Remove mentions about 'encoding' being non-Unicode.
Nvim doesn't support setting encoding=japan, so skip a test.

Problem:    Search() cannot skip over matches like searchpair() can.
Solution:   Add an optional "skip" argument. (Christian Brabandt, closes vim/vim#861)
https://github.com/vim/vim/commit/adc17a5f9d207fd1623fd923457a46efc9214777

Enable skip arg usage in autoload/freebasic.vim

evalarg_T doesn't really matter because it's deleted in v8.2.0918 (and
reincarnated for Vim9 script in v8.2.1047), but I found out too late :P Anyway:

- Port evalarg_T into eval.h and use const char * and Callback fields
- Use EVALARG_INIT to initialize
- Return bool over OK/FAIL from evalarg functions
- Remove check from evalarg_clean as callback_free ignores None callbacks anyway
- Move eva_buf field into evalarg_get as a local (not sure what reason it has
  being in the struct)

N/A patches for version.c:

vim-patch:8.2.4355: unnecessary call to check_colorcolumn()

Problem:    Unnecessary call to check_colorcolumn().
Solution:   Remove the call. (Sean Dewar, closes vim/vim#9748)
https://github.com/vim/vim/commit/0f7ff851cb721bb3c07261adbf82b591229f530d

vim-patch:8.2.{0882,1051,1083}: port `reduce()` function