Hard to pull error message from CallExecutionDetails

[austinabell]

There are methods to view each failure outcome, but even then it's janky to get to a result that can be used. ExecutionOutcome is not exactly easy to pull information needed.

Likely goes in tandem with #100 since the types for a lot of these can be avoided to be obfuscated as they are, because it's unclear to distinguish between result types

Also related to #131 since the error from execution is from the result, so the pattern is just that you have to format that error and not be able to distinguish where the error came from

Some of these issues can be seen from near/near-sdk-rs@3490844 (#789) commit