Make write Idempotent

[Xuanwo]

Write will always create files without returned file exists?

If we made this change, all our API will be Idempotent.

[JinnyYi]

Maybe we should change the writemode to WriteModeOverwrite in go-service-dropbox to overwrite the existing file instead of getting the path/conflict/file error?
ref: https://github.com/dropbox/dropbox-sdk-go-unofficial/blob/master/v6/dropbox/files/types.go#L5101-L5124

GitHub

dropbox/dropbox-sdk-go-unofficial

⚠️ An UNOFFICIAL Dropbox v2 API SDK for Go. Contribute to dropbox/dropbox-sdk-go-unofficial development by creating an account on GitHub.

[Xuanwo]

Maybe we could solve this problem together with #130.

Is it possible all API idempotent? (except API like CreateXxxx)?

[JinnyYi]

Write will always create files without returned file exists?

I'm confused about idempotent.
As for write, I think write is idempotent in go-service-*(exclude the services in alpha state, I'm not familiar with them) when multiple requests carry the same centent(In dropbox, the conflict occurs in the case where there's a file at the target path with contents different from the contents you're trying to write).

Creating files without returned file exists means overwrite or ignor the error when two write requests carry the different content?

[Xuanwo]

Tracked in beyondstorage/go-storage#624