feat(view): add view.width.padding (#1941)

* fix: variable width accounts for sign/number columns

* Add dynamic sizing padding options

with https://github.com/neovim/neovim/pull/20621 merged in it is now
possible to fully customize the status-column in nvim (the column on the
left containing line-numbers, fold info, signs and borders).

A fair few cool implementations have popped up like:
- https://github.com/CKolkey/config/blob/master/nvim/after/plugin/statuscolumn.lua
- https://github.com/luukvbaal/statuscol.nvim
- and my own personal one (based on CKolkey's fantastic work) https://git.hendrikpeter.net/hendrikpeter/pico-vim/-/blob/main/lua/peva/status_column.lua

The problem with nvim-tree however is that dynamic sizing doesn't take
the custom size of a status column into account and the end of file
names get clipped off. This little patch should fix that (and give some
examples to help other status_column modders get started).

Thanks for looking at this and thanks for making this amazing plugin,
I've been using it for a while and I really like it!

* allow padding function, update docs, rollback readme

* typo in example setup

* help formatting

---------

Co-authored-by: Alexander Courtis <alex@courtis.org>

doc/nvim-tree-lua.txt

@@ -81,6 +81,7 @@ Setup should be run in a lua file or in a |lua-heredoc| if using in a vim file.
     require("nvim-tree").setup({
       sort_by = "case_sensitive",
       view = {
+        width = 30,
         mappings = {
           list = {
             { key = "u", action = "dir_up" },
@@ -733,13 +734,17 @@ Window / buffer setup.
       Type: `string | number | function | table`, Default: `30`
 
         *nvim-tree.view.width.min*
-          Minimum dynamic width.
+        Minimum dynamic width.
           Type: `string | number | function`, Default: `30`
 
         *nvim-tree.view.width.max*
-          Maximum dynamic width, -1 for unbounded.
+        Maximum dynamic width, -1 for unbounded.
           Type: `string | number | function`, Default: `-1`
 
+        *nvim-tree.view.width.padding*
+        Extra padding to the right.
+          Type: `string | number | function`, Default: `1`
+
     *nvim-tree.view.side*
     Side of the tree, can be `"left"`, `"right"`.
       Type: `string`, Default: `"left"`