deterministic execution todos

[loredanacirstea]

• Stack traces should be logged in debug mode, but not included in the deterministic execution result.
• assess tinygo nondeterminism - e.g. maps order. what happens if a contract returns a map with a different order of keys per execution?
• move Date.now() from AssemblyScript environment and wasi clock_ apis + randomness APIs to their own host environment to be used only by consensusless contracts (e.g. consensus algorithms).
• simulate nondeterministic results and test that we reject the block; we should eliminate the tx from the mempool, but keep it as seen