Implement reload = true for custom functions

[stuckinsnow]

Hello, I am making this feature request as advised in another thread -- #2061. Reload = true does not currently work for custom functions, and there's a few cases I can think of where this could be useful:

• Quickfix menu
• Loclist menu
• Custom harpoon menu

Example loclist configuration --

  actions = {
    ["Ctrl-x"] = {
      noclose = true,
      fn = function(_, opts)
        local loclist = vim.fn.getloclist(0, { items = 0 }).items

        if not loclist or #loclist == 0 then
          print("Location list is empty.")
          return
        end

        local current_index = vim.fn.getloclist(0, { idx = 0 }).idx
        if current_index and loclist[current_index] then
          table.remove(loclist, current_index)
          vim.fn.setloclist(0, loclist, "r")
          print("Deleted item at index: " .. current_index)
        else
          print("Invalid selection.")
        end
        FzfLua.loclist(opts)
      end,
    }
  },

With a functional reload = true, the menu would no longer flash--much like how deleting buffers works.

[ibhagwan]

Converted to issue #2063, closing.