refactor!: rename "playground" => "dev" #23919

Problem:
"playground" is new jargon that overlaps with existing concepts:
"dev" (`:help dev`) and "view" (also "scratch" `:help scratch-buffer`) .

Solution:
We should consistently use "dev" as the namespace for where "developer
tools" live. For purposes of a "throwaway sandbox object", we can use
the name "view".
- Rename `TSPlayground` => `TSView`
- Rename `playground.lua` => `dev.lua`

runtime/lua/vim/treesitter.lua

@@ -493,7 +493,7 @@ end
 ---                        argument and should return a string.
 function M.inspect_tree(opts)
   ---@cast opts InspectTreeOpts
-  require('vim.treesitter.playground').inspect_tree(opts)
+  require('vim.treesitter.dev').inspect_tree(opts)
 end
 
 --- Returns the fold level for {lnum} in the current buffer. Can be set directly to 'foldexpr':