layers: Add Idx buffer alignment check to DrawState

At vkCmdBindIndexBuffer() time, verify that offset param falls on an aligment boundary as set by indexType param. New check enum is DRAWSTATE_VTX_INDEX_ALIGNMENT_ERROR.
Removed checks for this from the driver and added a validation test and documentation for the new check.
ParamChecker has a check to verify indexType param is an acceptable value, but it's after the call so documented a TODO for ParamChecker to push this check prior to call.
diff --git a/icd/intel/cmd_pipeline.c b/icd/intel/cmd_pipeline.c
index 4dc5abb..67bd7a8 100644
--- a/icd/intel/cmd_pipeline.c
+++ b/icd/intel/cmd_pipeline.c
@@ -263,18 +263,10 @@
         offset_align = 4;
         break;
     default:
-        /* TODOVV: Make sure covered in validation test */
-//        cmd_fail(cmd, VK_ERROR_INVALID_VALUE);
-        return;
+        assert(!"unsupported index type");
         break;
     }
 
-    if (offset % offset_align) {
-        /* TODOVV: Make sure covered in validation test */
-//        cmd_fail(cmd, VK_ERROR_INVALID_VALUE);
-        return;
-    }
-
     /* aligned and inclusive */
     end_offset = buf->size - (buf->size % offset_align) - 1;