boarc: nsim: add source code to initialize board and start os

Signed-off-by: Jingru <jingru@synopsys.com>

.vscode/settings.json

@@ -0,0 +1,6 @@
+{
+    "files.associations": {
+        "arc_exception.h": "c",
+        "arc_timer.h": "c"
+    }
+}