chore: add UNKNOWN error code

[maschad]

• Closes Create Unknown Error Code #2470
• Closes Add UNKNOWN error code and rawError property to FuelError #2521

This is the only specific use case I can currently see in the codebase. I'm not sure if any other error handling use cases apply at the moment @Torres-ssf

[petertonysmith94]

I'm not entirely sure about the issue #2470.

Potentially it's a duplicate of #2521?

[arboleya]

I'm not entirely sure about the issue #2470.
Potentially it's a duplicate of #2521?

@petertonysmith94 Almost, but not 100%.

The latter also requires the addition of the rawError property, which should be required for all FuelErrors.

[github-actions]

Coverage Report:

Lines	Branches	Functions	Statements
79.38%(-0.66%)	71.29%(-0.74%)	76.44%(-0.41%)	79.45%(-0.64%)

Changed Files:

Ok	File (✨=New File)	Lines	Branches	Functions	Statements
🔴	✨ apps/create-fuels-counter-guide/src/pages/predicate.tsx	0% (+0%)	0% (+0%)	0% (+0%)	0% (+0%)
🔴	packages/errors/src/test-utils/expect-to-throw-fuel-error.ts	95.83% (+0.83%)	94.44% (+1.59%)	100% (+0%)	95.83% (+0.83%)