allow to add arbitrary annotations

[migmartri]

Currently, we only allow adding annotations defined in the contract. Similarly to contractless attestations we should allow adding arbitrary annotations

[migmartri]

@Piskoo I am re-opening this issue since we want to also support adding arbitrary annotations in materials themselves, for example

chainloop att add --name test --value bar --kind string --annotation foo=bar 

Do you want to take it?

[Piskoo]

@Piskoo I am re-opening this issue since we want to also support adding arbitrary annotations in materials themselves, for example

chainloop att add --name test --value bar --kind string --annotation foo=bar 

Do you want to take it?

Sure!