Backblaze: Implement CopyFile

[dquintela]

What is your current rclone version (output from rclone version)?

rclone v1.46

• os/arch: windows/amd64
• go version: go1.11

What problem are you are trying to solve?

rclone's "backblaze" backend doesn't implement CopyFile. Per #2539, this inhibits the possibility of file and folder renames/moves, specially when using "rclone mount"

How do you think rclone should be changed to solve that?

The "backend" should implement the operation using the APIs announced today Backblaze B2 Copy File Beta is Now Public, and in particular to #2539, permit "Call Copy then Delete on each file if available" as described in @ncw comment #2539 (comment)

[dquintela]

Relates / Duplicates #3184

[coltonrb]

Duplicate of #3210 ?

[dquintela]

Duplicate of #3210 ?

Seems soo.. And almost finished :)

[ncw]

Yes this is a dupe. Can you use the other issue - I'll close this one now, thanks.