@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.
* @fif_codegen to match compiled.fif against an expected pattern
* @fif_codegen_avoid to ensure compiled.fif doesn't contain a substring
* both in Python and JS run_tests
* consider tests/codegen_check_demo.fc for examples
* fully refactor run_tests.py, make it extensible for the future
* an ability to write @compilation_should_fail tests
* an ability to launch run_tests.py for a single .fc file
* keep run_tests.js in sync with run_tests.py
* extract legacy_tests names/hashes to a separate file
shared between legacy_tester.py and legacy_tester.js