rename ContactPayload.coworker to ContactPayload.external

[huan]

Issue #2036 added a coworker?: boolean in ContactPayload, which I believe would be better to be renamed to external?: boolean according to #136

@windmemory Please let me know what you think, thank you very much.

[dosubot]

Hi, @huan. I'm Dosu, and I'm helping the wechaty team manage their backlog. I wanted to let you know that we are marking this issue as stale.

From what I understand, you opened this issue suggesting renaming the coworker property in ContactPayload to external and were looking for feedback on this proposed change. However, there hasn't been any activity or comments on the issue since then.

Could you please let us know if this issue is still relevant to the latest version of the wechaty repository? If it is, please comment on the issue to let us know. Otherwise, feel free to close the issue yourself, or the issue will be automatically closed in 7 days.

Thank you for your understanding and contribution to the wechaty community.