Instead of passing the signer as an argument to many methods on `Store`,
scope the `Store` itself to a signer.
This further allows to differentiate two different access modes on the
store in `radicle::cob::store::access`: `WriteAs` (which requires signer)
and `ReadOnly` (which does not require a signer).
The caches for issues and patches in `radicle::cob::{issue,patch}::Cache`
are concretised by removing the first type parameter, since it was
specific to issues and patches anyway. This was done in this commit as
it touches very similar usage sites.
Make `Device` less prominent, and instead lean more heavily towards
traits from the `signature` crate, such as `Keypair` and `Verifier`
in addition to `Signer`. Trait bounds regarding `Signer` could be
simplified, but this is left for the future.
In `radicle-cli`, the function `term::cob::patches_mut`, which generates
errors with a hint is used instead of the lower-level `Profile::patches_mut`.
Commands `rad issue cache` and `rad patch cache` now construct a
writeable cache on top of a read-only store.
Many knock-on changes are handled as well, to arrive at a clean state.
Lorenz Leutgeb