feat: Add exclude_unconfirmed and exclude_below_confirmations

[evanlinjin]

Fixes #143

Description

These are convenience methods on TxBuilder that can be used to filter out outpoints which do not meet a given confirmation threshold.

Previously, I advocated a feature freeze on TxBuilder, but I believe we can make an exception for these helper methods, as they do not broaden the TxBuilder interface’s error surface. Going forward, all other development should be directed to the bdk-tx repository and crate.

cc. @tnull

Changelog notice

Added:
- `TxBuilder::exclude_unconfirmed`
- `TxBuilder::exclude_below_confirmations`

Checklists

All Submissions:

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

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

[coveralls]

Pull Request Test Coverage Report for Build 15491418848

Details

• 92 of 95 (96.84%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 85.673%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
wallet/src/wallet/tx_builder.rs	92	95	96.84%

Totals
Change from base Build 15476130196:	0.1%
Covered Lines:	7469
Relevant Lines:	8718

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💛 - Coveralls