## Issue Addressed
NA
## Proposed Changes
Indicate that local keystores are `readonly: Some(false)` rather than `None` via the `/eth/v1/keystores` method on the VC API.
I'll mark this as backwards-incompat so we remember to mention it in the release notes. There aren't any type-level incompatibilities here, just a change in how Lighthouse responds to responses.
## Additional Info
- Blocked on #3464