[Unity][TVMScript] Fix Shape Var occurrence in Tensor annotation

[Ubospica]

Currently the script reports error

@I.ir_module
class Module:
    @R.function
    def main_adjoint(x: R.Tensor((3, 4), dtype="float32")):
        s: R.Shape([3, 2, 2]) = R.shape([3, 2, 2])
        lv: R.Tensor(s, dtype="float32") = R.reshape(x, s)
        return lv

because the relax parser cannot handle Var with ShapeExpr value occuring in R.Tensor annotations.

This PR specifically checks such cases in parser.

Thanks to the observation from @SiriusNEO

cc @Hzfengsy @tqchen

[tvm-bot]

Thanks for contributing to TVM! Please refer to the contributing guidelines https://tvm.apache.org/docs/contribute/ for useful information and tips. Please request code reviews from Reviewers by @-ing them in a comment.

• cc @Hzfengsy, @junrushao, @quic-sanirudh, @shingjan _{See #10317 for details}

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