Damien Neil 835b271169 reflect/protoreflect: add ExtensionType IsValid{Interface,Value} methods 7 lat temu
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protodesc 1799d1111a all: rename tag and flags for legacy support 7 lat temu
protoreflect 835b271169 reflect/protoreflect: add ExtensionType IsValid{Interface,Value} methods 6 lat temu
protoregistry 79bfdbe45b all: rename ExtensionType Descriptor method to TypeDescriptor (1/2) 7 lat temu