private static int skipAbsoluteShapeId(IdlInternalTokenizer tokenizer) {
        skipShapeIdNamespace(tokenizer);
        tokenizer.expect(IdlToken.POUND);
        tokenizer.next();
        return skipRelativeRootShapeId(tokenizer);
    }
Expects that the tokenizer is on a relative or absolute shape ID, skips over it, and returns a borrowed slice
of the shape ID.

@param tokenizer Tokenizer to consume and advance.
@return Returns the borrowed shape ID.
smithy-model/src/main/java/software/amazon/smithy/model/loader/IdlShapeIdParser.java