Hierarchical mode needs unit tests

[harrisonliew]

Currently, only this test exists:

hammer/src/hammer-vlsi/test.py

Line 775 in 95428fb

def test_hierarchical_width_height(self) -> None:

to make sure width/height match in hierarchical placement constraints. We need tests to at least ensure:

• Constraints in different modules don't clobber each other, especially if they're specified in different files (Hierarchical constraints not propagated correctly in certain circumstances #401)
• Global constraints vs. hierarchical constraints - precedence
• Meta directives (especially ones like prependlocal Support relative directory meta application inside hierarchical constraints #626)