fix(fzf-lua): ordering of messages in fzf

[sufftea]

Description

Message entries shown in fzf weren't sorted correctly.

Even though the messages are sorted initially, the order is broken when they are moved to ret:

  ---@type table<number, NoiceEntry>
  local ret = {}

  for _, message in ipairs(messages) do
    ret[message.id] = M.entry(message)
  end

I made find return a sorted list of NoiceEntry, and moved the part where the id to message map is created into open.

Related Issue(s)

I mentioned this problem in #1037, but this PR doesn't solve the main issue (yet)