refactor(#2826): move view to instanced window class (#3153)

* refactor(#2826): singleton View class, WIP

* refactor(#2826): singleton View class, WIP

* refactor(#2826): singleton View class, WIP

* refactor(#2826): singleton View class, WIP

* refactor(#2826): singleton View class, WIP

* refactor(#2826): singleton View class, WIP

* refactor(#2826): singleton View class, WIP

* refactor(#2826): singleton View class

* refactor(#2826): View is an Explorer member

* refactor(#2826): move autocmds to Explorer

* refactor(#2826): API uses Explorer's View

* refactor(#2826): move View into Explorer package

* refactor(#2826): retain necessary view globals

* refactor(#2826): move all winhl to appearance constants

* refactor(#2826): add lifecycle logging to all Explorer members

* refactor(#2826): fix bad cherry-pick

* refactor(#2826): better enumerate_options function

* refactor(#2826): add View.tab_line for debugging

* refactor(#2826): default lifecycle log off

* refactor(#2826): add experimental.multi_instance_debug, split globals out of view, move diagnostics to its own module

* refactor(#2826): instrument View:get_winnr

* refactor(#2826): instrument View:setup_tabpage

* refactor(#2826): instrument View:set_current_win, View:prevent_buffer_override

* refactor(#2826): instrument View:get_bufnr

* refactor(#2826): track member bufnr -> winid with global

* refactor(#2826): tidy experiment names and logs

* vim: nvim-tree: track bufnr via buffer-update channel

* vim: nvim-tree: more logging

* vim: nvim-tree: revert: track bufnr via buffer-update channel

* refactor(#2826): notify error on view winid and bufnr mismatches

* refactor(#2826): notify error on view winid and bufnr mismatches

* refactor(#2826): explorer init logging

lua/nvim-tree/help.lua

@@ -1,3 +1,4 @@
+local appearance = require("nvim-tree.appearance")
 local keymap = require("nvim-tree.keymap")
 local api = {} -- circular dependency
 
@@ -5,12 +6,6 @@ local PAT_MOUSE = "^<.*Mouse"
 local PAT_CTRL = "^<C%-"
 local PAT_SPECIAL = "^<.+"
 
-local WIN_HL = table.concat({
-  "NormalFloat:NvimTreeNormalFloat",
-  "WinSeparator:NvimTreeWinSeparator",
-  "CursorLine:NvimTreeCursorLine",
-}, ",")
-
 local namespace_help_id = vim.api.nvim_create_namespace("NvimTreeHelp")
 
 local M = {
@@ -210,7 +205,7 @@ local function open()
   })
 
   -- style it a bit like the tree
-  vim.wo[M.winnr].winhl = WIN_HL
+  vim.wo[M.winnr].winhl = appearance.WIN_HL_HELP
   vim.wo[M.winnr].cursorline = M.config.cursorline
 
   local function toggle_sort()