add support for --reuse to 'incus image copy [...] --copy-aliases' (like --reuse in 'incus publish')

[sltrash]

Is there an existing issue for this?

• There is no existing issue for this feature

What are you currently unable to do

When copying a image somewhere (different project or different incus server), the copy fails when a image with the same alias already exist on the destination:

incus image copy incus-01:my-template incus-02: --copy-aliases
Error: Failed remote image download: Alias already exists: my-template

As of now, the alias has to be deleted on the destination before the copy can happen.

What do you think would need to be added

An option like --reuse that 'incus publish' has:
incus image copy incus-01:my-template incus-02: --copy-aliases --reuse

The option would allow for the alias to be "updated" (associated to the copied image)

[rgerardi]

@stgraber can you please assign this to me?

[stgraber]

Done!