feat: option to auto-save files affected by will_rename_files (#218)

* save buffers changed by will_rename_files

* prevent closing already open buffers

* chore: move to config option

* chore: fixes

* fix: a crash and some formatting

---------

Co-authored-by: Steven Arcangeli <506791+stevearc@users.noreply.github.com>

lua/oil/config.lua

@@ -38,6 +38,9 @@ local default_config = {
   -- You can set the delay to false to disable cleanup entirely
   -- Note that the cleanup process only starts when none of the oil buffers are currently displayed
   cleanup_delay_ms = 2000,
+  -- Set to true to autosave buffers that are updated with LSP willRenameFiles
+  -- Set to "unmodified" to only save unmodified buffers
+  lsp_rename_autosave = false,
   -- Keymaps in oil buffer. Can be any value that `vim.keymap.set` accepts OR a table of keymap
   -- options with a `callback` (e.g. { callback = function() ... end, desc = "", mode = "n" })
   -- Additionally, if it is a string that matches "actions.<name>",