Need an assertion policy

Currently, we use `debug_assert` in most cases because we check the assertions in tests and we don't want to check them again in the release binary.

But it's not sustainable. Bugs will occur for any reason. It seems better to use `assert` to crash early because we have a plan to add [a bug tracker](https://github.com/CodeChain-io/codechain/issues/196).

I think we need a guideline to decide when to use `assert` or `debug_assert`.

Start by reviewing the current uses of `assert` and `debug_assert` across the Rust codebase, since the issue names no specific files or tests. Define the project guideline for choosing between them and document it in the project's appropriate guidance location; done means the policy is clear enough to apply consistently.

Written by the indexing model from the issue text.