✨ Allow running scripts that import other scripts with `typer` command

[atomiechen]

Issue

typer command cannot run a script which imports other scripts in the same directory, or in the subdirectory.

The original problem comes from https://github.com/tiangolo/typer-cli/discussions/142, and I still can reproduce this with typer version 0.12.3.

Changes I Made

• add sys.path.append(str(state.file.parent)) before exec_module
• add a test for this

You can check that the test won't pass without the modification of sys.path.