[FunC] Enrich testing framework, add code hash checking

@code_hash to match (boc) hash of compiled.fif against expected.
While being much less flexible than @fif_codegen, it nevertheless
gives a guarantee of bytecode stability on compiler modifications.

crypto/func/auto-tests/tests/s1.fc

@@ -51,4 +51,6 @@ _ main() {
 
 {-
 TESTCASE | 0 | | 0
+
+@code_hash 35542701048549611407499491204004197688673151742407097578098250360682143458214
 -}