Fix the cause of test_yamatanooroti randomly failing

[tompng]

When pressing tab key for a long time, cursor is moving right and left. On the right end, something(nt and ----) is remain displayed.

This behavior is also causing random test failure in rake test_yamatanooroti.
These tests failed in my local environment (macOS, Terminal.app, vterm 0.2, looks like fails more frequently compared to ci)

test_autocomplete_after_2nd_line
test_autowrap_in_the_middle_of_a_line
test_backspace
test_dynamic_prompt_returns_empty
test_dynamic_prompt_with_newline
test_finish_autowrapped_line_in_the_middle_of_multilines
test_force_enter
test_incremental_search_on_not_last_line
test_insert_line_in_the_middle_of_line
test_insert_newline_in_the_middle_of_buffer_just_after_dialog
test_mode_string_vi
test_mode_string_vi_changing
test_original_mode_string_vi
test_prompt
test_prompt_list_caching
test_prompt_with_escape_sequence
test_two_fullwidth
test_update_cursor_correctly_when_just_cursor_moving

I ran test_update_cursor_correctly_when_just_cursor_moving, the most frequently failing test in local for 100 times(local) and 50 times(ci in forked repository: tompng@da6b2c5, job result: https://github.com/tompng/reline/actions/runs/3307143383/jobs/5458548780)

result	local(100 runs)	ci(50 runs)	description
"Multiline REPL.\nprompt> def hoge\nprompt> 0123456789\n"	75	48	expected result
"Multiline REPL.\nprompt> def hoge^B\nprompt> 0123456789\n"	9	0	extra ^B
"Multiline REPL.\nprompt> def hog^N\nprompt> 0123456789\n"	9	2	extra ^N
"Multiline REPL.\nprompt> def hoge\nprompt> def hoge^B\nprompt> 0123456789\n"	2	0	extra line and ^B
"Multiline REPL.\nprompt> def hog^NB\nprompt> 0123456789\n"	4	0	extra ^NB
"Multiline REPL.\nprompt> def hoge\nprompt> def hoge\nprompt> 0123456789\n"	1	0	extra line

Failing result sometimes contains ^B and ^N.
This is because getc in ansi.rb is using STDIN.raw{getc}, that means there is a non-raw time between the next getc.
When there is new input while rendering a dialog, prompt or something else, the input is echo-ed.
To fix this, reline should not echo while editing multiline.

Changes

I added Reline::IOGate.with_raw_input and used in Reline.readmultiline.
I used IO#raw, not IO#noecho. noecho will show a key mark cursor for password input in Terminal.app and iTerm2 and maybe other teminals.

In raw mode, \n will only move cursor down, not left-end of the next line and test_terminate_in_the_middle_of_lines will fail. So I added \r to method rerender in line_editor.rb

Added test writing a[delete]a[delete]a[delete]...(4000 times) to vterm.
In HEAD, it fails with

<"Multiline REPL.\n" + "prompt>\n"> expected but was
<"a^Ha^Ha^Ha^Ha^Ha^Ha^Ha^Ha^Ha^H\n" +
"a^Ha^Ha^Ha^Ha^Ha^Ha^Ha^Ha^Ha^H\n" +
"a^Ha^Ha^Ha^Ha^Ha^Ha^Ha^Ha^Ha^H\n" +
"a^Ha^Ha^Ha^Ha^Ha^Ha^Ha^Ha^Ha^H\n" +
"prompt>\n">

failed result: https://github.com/tompng/reline/actions/runs/3307571761/jobs/5459304761

[tompng]

ruby/irb#445

2. Makes backspacing slow (mentioned multiple times in the poll comments)

I think cooked mode is making backspace ignored (not sent to remote server), and this pull request might improve it.

[hasumikin]

@tompng
(This is just to clarify)
The original issue, jumping cursor and remaining ==== and nt, seems not to happen on Linux and Windows (I now don't have a Mac).
Do you figure out if it's a Mac-specific issue?

[tompng]

@hasumikin
I only figure it out on Mac (I have mac only), so I don't know. It reproduced in Terminal.app, iTerm2, Alacaritty and Terminal in VSCode.
I think it's because of my keyboard key repeat setting and cpu speed. It only reproduced when I set key repeat speed to maximum in system preference. With this monkey-patch pasted to bin/console, it reproduced in slower key repeat speed

# jumping cursors
Reline::LineEditor.prepend Module.new{
  def render_dialog(...); sleep 0.2; super(...); end
}

# remaining strings
class Reline::LineEditor::Dialog
  def contents;sleep 0.005;@contents;end
end

[ima1zumi]

I checked on macOS, and Linux is also Reline::ANSI, so I think it's ok.
Please wait for a while I check it in Windows. I recently got a Windows license.

[hasumikin]

It works fine on Windows.