## Issue Addressed
#4635
## Proposed Changes
Wrap the `SignedVoluntaryExit` object in a `GenericResponse` container, adding an additional `data` layer, to ensure compliance with the key manager API specification.
The new response would look like this:
```json
{"data":{"message":{"epoch":"196868","validator_index":"505597"},"signature":"0xhexsig"}}
```
This is a backward incompatible change and will affect Siren as well.
c4e907de9f