refactor: refactor RTL paths and update test descriptions

- Updated RTL paths in various files to remove the 'ribp' prefix, reflecting the new directory structure.
- Modified test descriptions to remove version indicators (e.g., V2, V3) for clarity and consistency.
- Adjusted file references in scripts and tests to align with the new peripheral and multimedia directory structure.
- Added a new test to ensure repository layout invariants, confirming the absence of deprecated paths.

tests/test_clint.py

@@ -9,7 +9,7 @@ from pathlib import Path
 
 
 ROOT = Path(__file__).resolve().parents[1]
-PERIPHERAL = ROOT / "rtl/ip/ribp/peripheral"
+PERIPHERAL = ROOT / "rtl/ip/peripheral"
 
 
 def test_clint_standard_map_multi_hart_and_timebase(tmp_path: Path) -> None: