Problem: files were always created with mode 0644 and directories
with 0755, hardcoded in fs.touch and uv.fs_mkdir. Users who need
different defaults (e.g. 0600 for security) had no config option.
Solution: add new_file_mode (default 420 = 0644) and new_dir_mode
(default 493 = 0755) config options, passed through to fs.touch and
uv.fs_mkdir in the files and mac trash adapters. The fs.touch
signature accepts an optional mode parameter with backwards
compatibility (detects function argument to support old callers).
Local cache directories (SSH, S3) continue using standard system
permissions rather than the user-configured mode.
Based on: stevearc/oil.nvim#537
* wip: skeleton code for trash adapter
* refactor: split trash implementation for mac and linux
* fix: ensure we create the .Trash/$uid dir
* feat: code complete linux trash implementation
* doc: write up trash features
* feat: code complete mac trash implementation
* cleanup: remove previous, terrible, undocumented trash feature
* fix: always disabled trash
* feat: show original path of trashed files
* doc: add a note about calling actions directly
* fix: bugs in trash implementation
* fix: schedule_wrap in mac trash
* doc: fix typo and line wrapping
* fix: parsing of arguments to :Oil command
* doc: small documentation tweaks
* doc: fix awkward wording in the toggle_trash action
* fix: warning on Windows when delete_to_trash = true
* feat: :Oil --trash can open specific trash directories
* fix: show all trash files in device root
* fix: trash mtime should be sortable
* fix: shorten_path handles optional trailing slash
* refactor: overhaul the UI
* fix: keep trash original path vtext from stacking
* refactor: replace disable_changes with an error filter
* fix: shorten path names in home directory relative to root
* doc: small README format changes
* cleanup: remove unnecessary preserve_undo logic
* test: add a functional test for the freedesktop trash adapter
* test: more functional tests for trash
* fix: schedule a callback to avoid main loop error
* refactor: clean up mutator logic
* doc: some comments and type annotations
