[vulkan] Print note about module load times. NFC. (#1862)

Print a note ahead of a potentially long inactivity to set the right expectations.

Separately, we should add progress to the UI and make this loading faster.

shark/iree_utils/compile_utils.py

@@ -404,6 +404,11 @@ def load_vmfb_using_mmap(
             dl.log(f"mmap {flatbuffer_blob_or_path}")
             ctx = ireert.SystemContext(config=config)
             dl.log(f"ireert.SystemContext created")
+            if "vulkan" in device:
+                # Vulkan pipeline creation consumes significant amount of time.
+                print(
+                    "\tCompiling Vulkan shaders. This may take a few minutes."
+                )
             ctx.add_vm_module(mmaped_vmfb)
             dl.log(f"module initialized")
             mmaped_vmfb = getattr(ctx.modules, mmaped_vmfb.name)