Rewrite big tests to lua (as much as possible)

test/big/bitset.result

test/big/bitset.test

test/big/hash.result

test/big/hash.test

test/big/hash_multipart.result

test/big/hash_multipart.test

test/big/iterator.result

test/big/iterator.test

test/big/lua.result

test/big/lua.test

test/big/lua/bitset.lua

test/big/lua/index_random_test.lua

test/big/lua/push.lua

test/big/lua/utils.lua

test/big/suite.ini

test/big/tree_pk.result

test/big/tree_pk.test

test/big/tree_pk_multipart.result

test/big/tree_pk_multipart.test

test/big/tree_variants.result