add UUID miner

[mononaut]

(builds on #87)

draft PR to add a regex-based match for an unknown but clearly identifiable miner/pool with rotating addresses and rotating hexadecimal v4 UUIDs in the coinbase in the format: ://ffffffff-ffff-ffff-ffff-ffffffffffff (encoded in ASCII).

this entity makes up the overwhelming majority of "unknown" blocks in recent months (mining a total of 167 blocks so far), inflating the "unknown" share of blocks to ~1-2% at times.

although they've rotated through at least 3 different payout addresses so far, this is clearly a single entity from the consistency of the UUID scheme, the surrounding structure of the coinbase, and the fact that these payout addresses cluster around the same custodian.

I believe this will be the first use of a regex expression in the "tags" field rather than a simple string match, so we'll need to:

• confirm this doesn't break anything (although the README does document that "tags" are supposed to be regular expressions)
• probably improve rendering/display of actual regex tags on the mempool.space/mining/pool/... page.

The regex alone seems to match all relevant blocks without any false positives, but might need a bit of monitoring in case some other entity starts using a similar scheme.

It would also be nice to identify who this actually is, but I think it would still be informative to group their blocks under a pseudonym in the meantime.

(note: the consistent "h" near the start of the ASCII-decoded coinbase scriptsig isn't part of this miner's UUID pattern, but comes from the most significant byte of a 32-bit little-endian timestamp pushed immediately before the UUID data)

[mononaut]

see also: bitcoin-data#119