Backport lib/reline, and lib/irb for 3.0.1 3rd (#4228)

* [ruby/irb] Suppress error when File::ALT_SEPARATOR is nil

96accf3b95

* [ruby/irb] Suppress colorize on Windows tests

5be9354cf9

* [ruby/irb] The command "irb_info" should show RUBY_PLATFORM

39d1cd874f

* [ruby/irb] Fix inverse separator condition

33f933196f

* [ruby/reline] Return 1 when char width not found

This fixes ruby/reline#261.

3cf1213014

* [ruby/reline] Avoid tripping over nil prompt

d4d9d3e3d4

* [ruby/reline] Move script files for yamatanooroti tests

03031b885d

* [ruby/reline] Add a test for suppressing crash when dynamic prompt returns empty

ref. https://github.com/ruby/reline/pull/262

b98bc3c329

* [ruby/reline] We still need support new and legacy behavior.
Revert "Support for change in Windows-specific behavior at eol"

This reverts commit cad4de6ee841b43f3f0e441626f9415c3eda0f82.

646587fc2c

* [ruby/reline] check ENABLE_VIRTUAL_TERMINAL_PROCESSING flag and switch eof processing

3535676689

* [ruby/reline] Use UTF-8 only for width calc, rest uses original encoding

I confirmed that libvterm supports only which are UTF-8, US ASCII, UK, and
DEC graphics by reading source code, so can't test this patch by
yamatanoorogi gem through vterm gem for now.

This fixes ruby/irb#190.

44596c0cc7

* [ruby/reline] fix Reline::Windows.getconsolemode buffer

use double quotes to properly convert the \000 escape sequence.

236dfe5683

* [ruby/irb] Version 1.3.4

ab9852ccc5

* [ruby/reline] Version 0.2.4

462f971bd3

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
Co-authored-by: Eamonn Webster <eamonn.webster@gmail.com>
Co-authored-by: Yoshinao Muramatu <ysno@ac.auone-net.jp>
Co-authored-by: cremno <cremno@mail.ru>

lib/reline/unicode.rb

@@ -108,6 +108,7 @@ class Reline::Unicode
     end
     m = mbchar.encode(Encoding::UTF_8).match(MBCharWidthRE)
     case
+    when m.nil? then 1 # TODO should be U+FFFD <20> REPLACEMENT CHARACTER
     when m[:width_2_1], m[:width_2_2] then 2
     when m[:width_3] then 3
     when m[:width_0] then 0