[feature] return a proper errors instead of debug asserts

[MCJOHN974]

Description

Closes: #1164

Changes

Testing Information

Checklist:

• I have performed a self-review of my code
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[MCJOHN974]

I will replace other debug_assert_* in another commits, WIP

[djordon]

I will replace other debug_assert_* in another commits, WIP

Before replacing them, try to figure out whether we should just remove them instead. That's a little harder to do, but give it a shot.

[MCJOHN974]

With all this changes we will have only one debug_assert in the codebase:

sbtc/signer/src/bitcoin/validation.rs

Line 374 in e4c6b5f

debug_assert_eq!(self.deposit_sighashes.len(), self.reports.deposits.len());

Since the function where it is located do not return a Result but just a Vec we are okish to just panic inside this function which debug_assert will do.

[MCJOHN974]

@djordon thanks for your comments! I think last commit fixes issues you mentioned

[djordon]

Looks good, I just had one rewording comment.