Add Wallet.sign_deterministic, deterministic nonces

[SethDusek]

Add support for deterministic nonces for environments where RNG is not available. Note that this is only possible to do safely in single-signer scenarios (so multi-sigs can not be signed with this). The nonce generation algorithm is taken from BIP340 https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki#default-signing

[coveralls]

Pull Request Test Coverage Report for Build 11959180167

Details

• 44 of 52 (84.62%) changed or added relevant lines in 3 files are covered.
• 13 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.1%) to 78.782%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
ergo-lib/src/wallet/deterministic.rs	19	27	70.37%

Files with Coverage Reduction	New Missed Lines	%
ergo-p2p/src/peer_info.rs	1	68.42%
ergotree-ir/src/serialization/types.rs	6	81.88%
ergo-p2p/src/peer_spec.rs	6	76.56%

Totals
Change from base Build 11817168621:	0.1%
Covered Lines:	11083
Relevant Lines:	14068

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💛 - Coveralls