Batch claim much more aggressively even on pinnable outputs

Batch claim much more aggressively even on pinnable outputs

When we first added batch claiming, we only did so for claims which
we thought were not pinnable, i.e. those for which only we can
claim the output.

This was the conservative choice - any outputs which we think are
potentially pinnable might be pinned, leaving our entire batch
unable to confirm on chain. However, if we assume that pinnable
outputs are, indeed pinnable, and attempts to pin a transaction and
keep it from confirming have highly correlated success rates,
there's no reason we shouldn't also batch claims of pinnable
outputs separately.

Sadly, aggregating other types of inputs is rather nontrivial, as
evidenced by the size of this commit -

HTLC-Timeout claims have locktimes fixed by our counterparty's
signature and thus can only be aggregated with other HTLCs of the
same CLTV, which we have to check for.

Further, our concept of "pinnable" is deliberately somewhat fuzzy -
outputs which we believe are not pinnable will eventually become
pinnable at the height where our counterparty can spend them. Thus,
we treat outputs as pinnable if they're over that height, and if
they're within `COUNTERPARTY_CLAIMABLE_WITHIN_BLOCKS_PINNABLE` of
that height we treat them as neither pinnable nor not-pinnable,
aggregating such claims only with other claims which will become
pinnable at the same height.

However, the complexity required is worth it - aggregation can save
our users a lot of money in the case of a force-close, and directly
impacts the amount of UTXOs they need as reserve for anchors, so we
want to aggregate as much as possible.

Fixes #3064