Update LND, Aperture, and Taproot Assets to revisions using the
btcd v2 modules, and update lndclient to v0.21.0-3. Migrate Loop
chain, transaction, and address types to their corresponding v2
packages.
The lndclient release includes the migration from:
https://github.com/lightninglabs/lndclient/pull/280
Taproot Assets is temporarily replaced with its btcd v2 revision
because the v0.8 release branch has not adopted the new modules.
This raises the minimum Go version to 1.26 and changes exported
address types.
