feat(Squirrel cli): add --ascii, --nascii and --getascii

[Parsifa1]

ref #797 #123
close #774

add --ascii --nascii getascii

api 参考了 rime/weasel#1113

我不是特别了解swift

该pr在 ai 的辅助下完成 我在本地测试了这几个功能 如果有写的不符合普遍范式的情况可以直接修改或者review提出来（

[Parsifa1]

cal be used in :

local current = vim.fn.system "/Library/Input\\ Methods/Squirrel.app/Contents/MacOS/Squirrel --getascii"

function Switch_to_English_input_method()
  current = vim.fn.system "/Library/Input\\ Methods/Squirrel.app/Contents/MacOS/Squirrel --getascii"
  if current ~= "ascii" then
    vim.fn.system "/Library/Input\\ Methods/Squirrel.app/Contents/MacOS/Squirrel --ascii"
  end
end

function Set_input_method()
  if current ~= "ascii" then
    vim.fn.system(
      "/Library/Input\\ Methods/Squirrel.app/Contents/MacOS/Squirrel --" .. string.gsub(current, "\n", "")
    )
  end
end

vim.cmd [[
augroup input_method
  autocmd!
  autocmd InsertEnter * :lua Set_input_method()
  autocmd InsertLeave * :lua Switch_to_English_input_method()
augroup END
]]