Anchor commitments 2024

[ecdsa]

this was rebased in july 2024 from #7509
I guess it needs to be rebased again :-)

Here are my personal notes regarding this rebase:

• some tests are broken (REDEEMED state reached too early in test_breach)
• we should use password in memory (daemon unlock command)
• if no password in memory (non-android GUI): maybe warn user?
• stop LN support for watching-only and hardware wallets

[ecdsa]

Notes about this merge:

• commits were merged individually (there is no merge commit).
• anchor outputs can be activated by config variable enable_anchor_channels
• unit tests are performed both with and without anchors. However, regtest are run only with anchors. (unlike in the original PR)
• the commit that reorders functions in lnsweep was left out due to difficulty rebasing.
• password-storing code was left out. Instead, htlc sweeping assumes that the wallet is unlocked, and calls wallet.get_unlocked_password()
• a confusion between sats and msats was fixed (see FIXED_ANCHOR_SAT)
• the for loop calling extract_preimage_from_htlc in f4ebe6e was left out.