Add state sync support (#7166)

* Add state sync support

* fix incorrect test tempdir

* proto: move and update Protobuf schemas

* proto: lint fixes

* comment tweaks

* don't use type aliasing

* don't call .Error() when logging errors

* use create terminology instead of take for snapshots

* reuse chunk hasher

* simplify key encoding code

* track chunk index in Manager

* add restoreDone message for Manager

* add a ready channel to Snapshotter.Restore()

* add comment on streaming IO API

* use sdkerrors for error handling

* fix incorrect error

* tweak changelog

* syntax fix

* update test code after merge

types/errors/errors.go

@@ -123,6 +123,14 @@ var (
 	// ErrUnpackAny defines an error when unpacking a protobuf message from Any fails.
 	ErrUnpackAny = Register(RootCodespace, 34, "failed unpacking protobuf message from Any")
 
+	// ErrLogic defines an internal logic error, e.g. an invariant or assertion
+	// that is violated. It is a programmer error, not a user-facing error.
+	ErrLogic = Register(RootCodespace, 35, "internal logic error")
+
+	// ErrConflict defines a conflict error, e.g. when two goroutines try to access
+	// the same resource and one of them fails.
+	ErrConflict = Register(RootCodespace, 36, "conflict")
+
 	// ErrPanic is only set when we recover from a panic, so we know to
 	// redact potentially sensitive system info
 	ErrPanic = Register(UndefinedCodespace, 111222, "panic")