Error handling for missing outputDescription or spendingDescription

[ty-everett]

Currently errors are very couterintuitive when spendingDescription (on inputs) or outputDescription (on outputs) is missing.

Something like "cannot read .trim of undefined.

Should be "A [spending/output]Description is required on all [inputs/outputs]."

[sirdeggen]

This could be generalized as an approach - input validation. At the moment it's predominantly type checking, which is fine if you're building in typescript but I've seen a fair few devs hit this one while in javascript.

[sirdeggen]

Proposal: move this to ts-sdk because that's where input validation could happen within WalletClient methods?

[tonesnotes]

validationHelpers moved to ts-sdk on validateArgs branch.
Confirmed missing outputDescription parameter error is clearly identified in new unit test.