Implement RENAME in the GCS backend

[mdirkse]

Currently unimplemented. See here: https://github.com/bolcom/libunftp/blob/b53478b8ecb8b61ac7685816e70011ed979484b8/crates/unftp-sbe-gcs/src/lib.rs#L358

[HenrikOssipoff]

Hi, we stumbled across unftp recently and must say we're very happy! If at all this one in particular could become a priority, that would be greatly appreciated 🙏🏻 Thank you for creating this.

[robklg]

Hi @HenrikOssipoff great to hear! Do keep in mind that a rename action would not be atomic, the GCS backend doesn't support this, and so a rename would consist of two operations: copy+delete. I can't promise we can pick this up very soon, but I will try to get it some more priority.

[HenrikOssipoff]

@robklg Makes perfect sense - we've rewritten our uses of the MOVE command to download -> uploade -> delete anyway.

Once again, thanks for creating this. unftp greatly simplified running FTP on our environment.

[robklg]

We're very pleased to hear that :-)