Reorganize test dir to ensure test of installed pkg

tests/lib/cpuifs/apb3/__init__.py

@@ -0,0 +1,18 @@
+from ..base import CpuifTestMode
+
+from peakrdl.regblock.cpuif.apb3 import APB3_Cpuif, APB3_Cpuif_flattened
+
+class APB3(CpuifTestMode):
+    cpuif_cls = APB3_Cpuif
+    rtl_files = [
+        "apb3_intf.sv",
+    ]
+    tb_files = [
+        "apb3_intf.sv",
+        "apb3_intf_driver.sv",
+    ]
+    tb_template = "tb_inst.sv"
+
+class FlatAPB3(APB3):
+    cpuif_cls = APB3_Cpuif_flattened
+    rtl_files = []