test: Move bump fee + foreign utxo tests

[ValuedMammal]

These files are added to wallet/tests directory

• add_foreign_utxo.rs
• build_fee_bump.rs
• common.rs

fixes #21
fixes #238

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

[coveralls]

Pull Request Test Coverage Report for Build 14324315948

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 86.525%

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Totals
Change from base Build 14270666930:	0.0%
Covered Lines:	7269
Relevant Lines:	8401

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💛 - Coveralls

[tvpeter]

Could you consider separating the taproot-related test cases into a different module? There are many test cases associated with taproot.

[tvpeter]

tACK 22e28b2

Thank you for working on this Mammal.

I did not proceed with #238 since they are related.

There are some warnings related to bitcoin::key::TweakedKeypair::to_inner but once you rebase, they should be gone.

I have left a comment on whether it is a good idea to separate taproot-related test cases into their module.

Thank you