add wasmtime trap information on function call errors, if available

[tessi]

Function call errors into web assembly now have more detail if wasmtimes trap information is available. This helps, for example, when using fuel and the wasmtime store is out of fuel:

Error during function excecution (wasm trap: all fuel consumed by WebAssembly): error while executing at wasm backtrace:
    0: 0x3618 - wasmex_test.wasm!void

The new information is added in parenthesis just after the Error during function excecution message.

See: #617

[superchris]

This seems really nice! I might like to do something very similar in the components code, turning traps (eg when wasi is needed but not present) into proper error tuples would be lovely

[tessi]

thanks @superchris now that at least one person thinks this is helpful, let's merge :)