refactor: commands such as :GoGet runs with new runner

lua/gopher/_utils/runner/init.lua

@@ -0,0 +1,30 @@
+local Job = require "plenary.job"
+local runner = {}
+
+---@class gopher.RunnerOpts
+---@field args? string[]
+---@field cwd? string?
+---@field on_exit? fun(data:string, status:number)
+
+---@param cmd string
+---@param opts gopher.RunnerOpts
+---@return string[]|nil
+function runner.sync(cmd, opts)
+  local output
+  Job:new({
+    command = cmd,
+    args = opts.args,
+    cwd = opts.cwd,
+    on_exit = function(data, status)
+      output = data:result()
+      vim.schedule(function()
+        if opts.on_exit then
+          opts.on_exit(output, status)
+        end
+      end)
+    end,
+  }):sync()
+  return output
+end
+
+return runner