[Backend][Vitis] Fix Vitis input data and expose target to pytorch frontend

[chhzh123]

Description

This PR adds the following two features:

1. Dump input data to file so Vitis on-board execution can directly read from files without recompiling the host program.
2. Expose Vitis target to the Pytorch frontend, so users can specify the target to build the hardware design.

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