Backport binary proto serialization/deserialization code

In order to prepare for protobuf editions support, we are backporting
our binary serialization and deserialization libraries (and associated
tests). The newer code includes several years worth of improvements
that improve the overall conformance findings.

Author: dibenede

binary/any_field_type.js

@@ -0,0 +1,14 @@
+goog.module('jspb.binary.any_field_type');
+
+const {RepeatedFieldType} = goog.require('jspb.binary.repeated_field_type');
+const {ScalarFieldType} = goog.requireType('jspb.binary.scalar_field_type');
+
+
+/**
+ * A field in jspb can be a scalar, a block of bytes, another proto, or an
+ * array of any of the above.
+ * @typedef {?ScalarFieldType|?RepeatedFieldType|!Uint8Array}
+ */
+let AnyFieldType;
+
+exports = {AnyFieldType};