It's part of the presentation logic of the cli, and only used internally.
We can consider providing utilities for these, but better as part of
separate packages.
This deprecates the following types and functions:
- `SignedTagInfo`
- `SignerInfo`
- `NewTrustTagFormat`
- `NewSignerInfoFormat`
- `TagWrite`
- `SignerInfoWrite`
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>