Support minting on Ledger signing device

[guggero]

Depends on #1290.
Depends on #1295.

Adds the necessary meta information to the group key VM transaction PSBT to allow signing of such a mint authorization transaction using a custom version of the HWI library and a Ledger signing device.

A new guide documents the required steps.

[coveralls]

Pull Request Test Coverage Report for Build 12833451443

Details

• 33 of 134 (24.63%) changed or added relevant lines in 1 file are covered.
• 58 unchanged lines in 10 files lost coverage.
• Overall coverage decreased (-0.09%) to 40.742%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tapgarden/planter.go	33	134	24.63%

Files with Coverage Reduction	New Missed Lines	%
tappsbt/create.go	2	53.22%
tapchannel/aux_leaf_signer.go	2	43.08%
fn/option.go	3	43.3%
tapgarden/planter.go	4	65.02%
commitment/tap.go	4	83.86%
tapchannel/aux_invoice_manager.go	6	83.25%
tapdb/multiverse.go	6	68.21%
asset/asset.go	8	76.9%
universe/interface.go	10	52.81%
asset/mock.go	13	91.25%

Totals
Change from base Build 12831178104:	-0.09%
Covered Lines:	26641
Relevant Lines:	65390

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💛 - Coveralls

[guggero]

Changed the base branch to sealbatch-signed-group-psbt (#1295) since that gives us the nicer user experience and simplifies the signing guide for the Ledger as well.