Canonical LC (#15585)

* create lc cache to track branches

* save lc stuff

* remove finalized data from LC cache on finalization

* read lc stuff

* edit tests

* changelog

* linter

* address commments

* address commments 2

* address commments 3

* address commments 4

* lint

* address commments 5 x_x

* set beacon lcStore to mimick registrable services

* clean up the error propagation

* pass the state to saveLCBootstrap since it's not saved in db yet

consensus-types/light-client/update.go

@@ -89,6 +89,10 @@ func NewWrappedUpdateAltair(p *pb.LightClientUpdateAltair) (interfaces.LightClie
 	}, nil
 }
 
+func (u *updateAltair) IsNil() bool {
+	return u == nil || u.p == nil
+}
+
 func (u *updateAltair) MarshalSSZTo(dst []byte) ([]byte, error) {
 	return u.p.MarshalSSZTo(dst)
 }
@@ -256,6 +260,10 @@ func NewWrappedUpdateCapella(p *pb.LightClientUpdateCapella) (interfaces.LightCl
 	}, nil
 }
 
+func (u *updateCapella) IsNil() bool {
+	return u == nil || u.p == nil
+}
+
 func (u *updateCapella) MarshalSSZTo(dst []byte) ([]byte, error) {
 	return u.p.MarshalSSZTo(dst)
 }
@@ -423,6 +431,10 @@ func NewWrappedUpdateDeneb(p *pb.LightClientUpdateDeneb) (interfaces.LightClient
 	}, nil
 }
 
+func (u *updateDeneb) IsNil() bool {
+	return u == nil || u.p == nil
+}
+
 func (u *updateDeneb) MarshalSSZTo(dst []byte) ([]byte, error) {
 	return u.p.MarshalSSZTo(dst)
 }
@@ -591,6 +603,10 @@ func NewWrappedUpdateElectra(p *pb.LightClientUpdateElectra) (interfaces.LightCl
 	}, nil
 }
 
+func (u *updateElectra) IsNil() bool {
+	return u == nil || u.p == nil
+}
+
 func (u *updateElectra) MarshalSSZTo(dst []byte) ([]byte, error) {
 	return u.p.MarshalSSZTo(dst)
 }