rename DeserializeIdentity to IdentityResolver

Rename the following interface and method

```go
type IdentityDeserializer interface {
// DeserializeIdentity deserializes an identity.
// Deserialization will fail if the identity is associated to
// an msp that is different from this one that is performing
// the deserialization.
DeserializeIdentity(identity *applicationpb.Identity) (Identity, error)

// GetKnownDeserializedIdentity returns a known identity matching the given IdentityIdentifier.
GetKnownDeserializedIdentity(IdentityIdentifier) Identity

// IsWellFormed checks if the given identity can be deserialized into its provider-specific form
IsWellFormed(identity *applicationpb.Identity) error
}
```

to

```go

type IdentityResolver interface {
// Resolve converts a proto identity into a usable domain Identity.
// It returns an error if the identity belongs to a different MSP.
Resolve(id *applicationpb.Identity) (Identity, error)

// Lookup returns a known identity matching the given identifier.
Lookup(id IdentityIdentifier) Identity

// Validate checks if the given identity is well-formed and valid for this provider.
Validate(id *applicationpb.Identity) error
}
```