bug#61368: [PATCH] Extend go-ts-mode with support for pre-filling return statements

[Evgeni Kolev]

Thank you João for the input! I think something like this would make
sense in go-ts-mode.el:
```
(with-eval-after-load 'yasnippet
  (yas-define-snippets 'go-ts-mode
                       '(("return" (yas-expand-snippet
                                    (go-ts-mode-return)))
                         ("iferr" (yas-expand-snippet
                                   (format "if err != nil {\n%s\n}"
                                           (go-ts-mode-return)))))))
```

A custom variable go-ts-mode-want-yasnippet could be added to
optionally prevent adding the snippets.

Eli, would you consider something like the code above acceptable as an
alternative to an electric "return" mode?

Having optional yasnippet integration was also brought up by Theo in
this message[1] and this one [2].

[1]: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=60805#11
[2]: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=60805#17