mint: add seed decrypt #200

Job	Run time
checks / mypy	46s
checks / formatting	33s
checks / ruff	9s
regtest (3.10, 1.7.1, CoreLightningRestWallet) / regtest	3m 29s
regtest (3.10, 1.7.1, LNbitsWallet) / regtest	3m 14s
regtest (3.10, 1.7.1, LndRestWallet) / regtest	2m 58s
tests (ubuntu-latest, 3.10, 1.7.1, false, true, FakeWallet) / Run (mint-cache-secrets false, mint-only-deprecated true)	2m 13s
tests (ubuntu-latest, 3.10, 1.7.1, true, false, FakeWallet) / Run (mint-cache-secrets true, mint-only-deprecated false)	1m 57s
tests (ubuntu-latest, 3.10, 1.7.1, true, true, FakeWallet) / Run (mint-cache-secrets true, mint-only-deprecated true)	2m 20s
tests (ubuntu-latest, 3.10, 1.7.1, false, false, FakeWallet) / Run (mint-cache-secrets false, mint-only-deprecated false)	1m 57s
	19m 36s

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