refactor: minimize amount of vimscript (#96)

* refactor: remove autoload

* since nvim 0.9 health.lua files are threaded as checkhealth provider

*  prof of concept 

* fix(runner.gocmd)!: i forgot to update it when i was working on #85

* fix(plugin): now commands register properly

* fix(plugin): fix command name for :GoIfErr

* fix(plugin): respect `setup_commands` option

* docs: update

* refactor(plugin): use vim.schedule

* docs: update CONTRIBUTING

doc/gopher.nvim.txt

@@ -61,6 +61,10 @@ You can look at default options |gopher.nvim-config-defaults|
     ---@type number
     timeout = 2000,
 
+    --- whether to setup plugin commands or not
+    ---@type boolean
+    setup_commands = true,
+
     -- user specified paths to binaries
     ---@class gopher.ConfigCommand
     commands = {