feat(flow): add DreamPlace macro placement step

[zhaoxueyan1]

Summary

• add an opt-in macro_rtl2gds flow with a dedicated macroPlacement step
• wire DreamPlace macro-only execution and selective snapshot writeback
• preserve the default rtl2gds flow and normal placement/legalization behavior
• update submodule pointers to the feature branches

Dependencies

• ECC-Tools PR refactor: delete ecc snapshot #178: feat(pyplacedb): support macro placement writeback ecc-tools#178
• ECC-DreamPlace PR fix(parameters): allow more desgin name in get_design_parameters #33: feat: add macro-only placement writeback ecc-dreamplace#33

Validation

• focused macro-placement and flow tests: 114 passed, 10 skipped, 1 xfailed
• Ruff and git diff --check passed
• native skips are due to the current GLIBC ABI mismatch

Unrelated large untracked directories were excluded.

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