Initial plan for adding libstatic support

Co-authored-by: luoliwoshang <51194195+luoliwoshang@users.noreply.github.com>

Author: Copilot

parser/testdata/func/hfile/forwarddecl.h.i

@@ -0,0 +1,10 @@
+# 1 "/home/runner/work/llcppg/llcppg/parser/testdata/func/hfile/forwarddecl.h"
+# 1 "<built-in>" 1
+# 1 "<built-in>" 3
+# 453 "<built-in>" 3
+# 1 "<command line>" 1
+# 1 "<built-in>" 2
+# 1 "/home/runner/work/llcppg/llcppg/parser/testdata/func/hfile/forwarddecl.h" 2
+void foo0();
+void foo1(int a);
+void foo2(int a,...);