[Relax] Fix the parser to avoid treating a list as an integer

[jikechao]

When the output tensor is in the form of (10), TVM will crash unexpectedly as follows.
This PR adds a rule to convert the (10) to (10,) to avoid such a crash!

Traceback (most recent call last):
  File "/share_container/optfuzz/res/ut_ut_test/res_executions/14832_test.py", line 9, in <module>
    class Module:
  File "/share_container/optfuzz/res/ut_ut_test/res_executions/14832_test.py", line 11, in Module
    def main(x: R.Tuple(R.Tensor((10,), dtype="float32"), R.Tensor((10,), dtype="float32"))) -> R.Tensor((10), dtype="float32"):
                                                                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/software/tvm/python/tvm/script/parser/relax/entry.py", line 266, in Tensor
    if shape is not None and not isinstance(shape, Var) and len(shape) == 0:
                                                            ^^^^^^^^^^
TypeError: object of type 'int' has no len()

from tvm.script import ir as I
from tvm.script import tir as T
from tvm.script import relax as R

@I.ir_module
class Module:
    @R.function
    def main(x: R.Tuple(R.Tensor((10,), dtype="float32"), R.Tensor((10), dtype="float32"))) -> R.Tensor((10), dtype="float32"):
        cls = Module
        with R.dataflow():
            lv: R.Tensor((10,), dtype="float32") = x[0]
            R.output(lv)
        return lv
mod = Module
mod.show()

cc @tqchen @Hzfengsy @Lunderberg @yongwww

[Hzfengsy]

Thanks for the contribution!

First, it's not a typical bug. (10) is just an integer rather than a list based on the Python syntax, while [10] and (10, ) are list and tuples. Here, we request a list as input, so the error is expected (based on the current implementation)

Second, it should be a valuable sugar for end users. But please:

1. consider supporting not only integers but also prim expr, symbolic shapes etc.
2. please add tests in the parser test file