[release] Allow deployable artifacts to be added as release assets

[aalmiray]

Is your feature request related to a problem? Please describe.
Allow files configured in the deploy section to be uploaded as release assets during release.

Describe the solution you'd like
Add a flag to a given deployer stating that its deployables should be treated as release assets. Additional information for filtering deployables (signatures, checksums, or by extension) may be required.

Describe alternatives you've considered
Configure deployables to be released as assets using the files section and globs.

WARNING: Uploads will also be affected, not just releases.

cc: @nipafx