Support Wildcard targets for COPY

[idodod]

Use case

We recently introduced support of wildcards in a target path when using BUILD on a target to ease execution of targets in a monorepo (See #3661).
It can be useful to do the same for COPY, e.g. :

VERSION 0.8

test:
    FROM alpine
    COPY --dir ./wildcard-build/*+get-files/* .

Expected Behavior

The behavior should be the same as it was implemented for BUILD

Note that if the different targets save an artifact to the same file/directory, the artifact may overwrite each other.
For this command to. be effective, the artifact needs to be saved in a different path.

[idodod]

will be included in next release (v0.8.8)