feat: allow custom input provider, removing dressing.nvim (#2173)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: yetone <yetoneful@gmail.com>

lua/avante/ui/input/providers/native.lua

@@ -0,0 +1,23 @@
+local M = {}
+
+---@param input avante.ui.Input
+function M.show(input)
+  local opts = {
+    prompt = input.title,
+    default = input.default,
+    completion = input.completion,
+  }
+
+  -- Note: Native vim.ui.input doesn't support concealing
+  -- For password input, users should use dressing or snacks providers
+  if input.conceal then
+    vim.notify_once(
+      "Native input provider doesn't support concealed input. Consider using 'dressing' or 'snacks' provider for password input.",
+      vim.log.levels.WARN
+    )
+  end
+
+  vim.ui.input(opts, input.on_submit)
+end
+
+return M