refactor(actions): common code for rename-file

[hinell]

actions-fs-rename-file-demo.mov

• required to proceed with feat(actions): git-aware cut / paste / rename fs actions #2542 PR
• Refactor lua/nvim-tree/actions/fs/rename-file.lua:
  • feat: Input_path_editor - new class
  • Deprecate private fn() in case it's used elsewhere
  • Replace fn() by rename_*() based on Input_path_editor new class
  • feat: new rename_relative, unbound by default

Input_path_editor new class

• Encapsulates reusable code from rename-file.lua used for editing chunks of absolute path per feat(actions): git-aware cut / paste / rename fs actions #2542 (comment)
• Despite looking complex in fact has only two methods that are used to prepare() / restore() path intended to be modified by user in vim.ui.input (see example)
• Reusable, extensible, well documented

Why class?

• it isolates temp data in instance-namespace, easy to use / extend
• it encapsulates state that can be passed around / referenced from across async callback functions without need to pollute local scope

Why prototype-based class?

• Prototype is a namespace of a class where instance methods are gathered / localized.

[alex-courtis]

See #2551 (comment)