Provide abort function to user

[chipshort]

One thing we can easily provide is a version of env::panic_str called cosmwasm_std::abort which immediately terminates the contract with the given message. In contrast to the panic handler and the panic! macro, this would avoid adding file paths and line numbers to the panic message. However, I'm not sure if this is good for unit testing as we suddenly need a way to handle those abortions in unit tests.

Originally posted by @webmaster128 in #1570 (comment)