Raise COINBASE_TYPE_YUGE to 32000 bytes and the coinbaser output limit to 1024

[iohzrd]

Based on #28, which is based on #24. Review the last commit. This is an alternative to #30: merge one of the two.

On BLAKE2b work every miner is served COINBASE_TYPE_YUGE, and the coinbase never reaches the miner, so no firmware limit applies to its size. This raises it. Fingerprinting and classes 1, 2, 3 and 5 are unchanged.

• MAX_DICTATED_COINBASE_SIZE is 32000 (YUGE was 16000). That holds 1024 P2WPKH outputs or about 740 taproot outputs.
• datum_stratum_coinbase_fit_to_template still cuts the coinbase to the template's room. At the node's default -blockreservedweight (8000 WU) that is about 1800 bytes on a full block. Filling 32000 bytes needs about 129000 WU, 16% of an 800000 WU RDTS block.
• MAX_COINBASER_OUTPUTS is 1024 (was 512). It sets the coinbaser parse limit and the size of available_coinbase_outputs.
• STRATUM_COINBASE2_MAX_LEN is 65536 hex characters (was 32768).
• MAX_POW_MESSAGE_SIZE (MAX_COINBASE_TXN_SIZE_BYTES + 4096) replaces 32768 as the size of datum_protocol_pow's message buffers and as the replay limit.
• DATUM_PROTOCOL_COINBASER_BUFFER_SIZE is 65536 (was 32768) for the coinbaser response, whose length field is a uint32.
• Test: 1024 P2WPKH outputs fit one coinbase, with a three-byte output count.

The pool server has to accept a share coinbase section (coinb1 + coinb2) of up to 31988 bytes, a share message of up to 33372 bytes (encrypted, with its pad), and a coinbaser response of up to 65535 bytes.

BSS goes from 89.4 MB to 130.4 MB.

The commit also reformats datum_stratum.h: Allman braces, and spaces for alignment.

Every commit builds with -Wall -Werror and passes --test.