[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/co1.fc

@@ -57,4 +57,6 @@ _ main() {
 
 {-
 TESTCASE | 0 | | 0
+
+@code_hash 98157584761932576648981760908342408003231747902562138202913714302941716912743
 -}