[Backend][Docs] Update Vitis HLS host code to support load/store data from/to files

[chhzh123]

Description

This PR fixes #162. It adds support to streamline the bitstream execution process from Python. Now users can directly pass in Numpy array and call the module/bitstream just like what they do for software testing.

This PR also fixes a bug of passing in scalars in the host code (related to #219).

Examples

import allo
from allo.ir.types import bool, int32
import numpy as np

def test_scalar_not_array():
    def top(inst: bool, C: int32[3]):
        flag: bool = inst[0]
        if flag:
            C[0] = C[0] + 1

    s = allo.customize(top)
    mod = s.build(target="vitis_hls", mode="hw", project="test_scalar.prj")
    C = np.array([1, 2, 3], dtype=np.int32)
    # execute the bitstream
    mod(1, C)
    np.testing.assert_allclose(C, [2, 2, 3], rtol=1e-5)
    print("Passed!")

test_scalar_not_array()

Checklist

• PR's title starts with a category (e.g. [Bugfix], [IR], [Builder], etc)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage (It would be better to provide ~2 different test cases to test the robustness of your code)
• Code is well-documented