Support `--except` argument in `bst artifact *` commands

Currently we consistently support the `--except` argument in any command which supports the `--deps` argument, except for the `bst build` command where it would not make sense.

For artifact commands, this is a little more tricky as we accept artifact names and we cannot reliably construct the entire build graph (as some artifacts in the tree might be remote, and we don't have the declarations for the originating elements on hand).

This issue is an acknowledgement of this shortcoming, perhaps there is a middle ground which can be reached where `bst artifact` commands can support `--except` only for targets specified by their in-tree element names.

This is marginally related to #1411

Start by reviewing the artifact commands and the existing --deps/--except handling. Determine whether support can be defined for targets named by in-tree elements despite remote artifacts lacking declarations. Done means the supported scope and behavior for artifact commands are specified and implemented with corresponding tests.

Written by the indexing model from the issue text.