v0.7.1 Added support for `go.work` and new `%cd` command

• Added support for tracking go.work, which allows auto-complete and contextual help
  to work with the local modules configured. It also requires gopls v0.12.4 or newer to work.
• Fixed auto-complete bug when no main function (or no %%) was present in cell.
• Added special command %cd to chance current directory.
• Commands %cd and %env prints results of its execution.