* log: fix formatting of big.Int
The implementation of formatLogfmtBigInt had two issues: it crashed when
the number was actually large enough to hit the big integer case, and
modified the big.Int while formatting it.
* log: don't call FormatLogfmtInt64 for int16
* log: separate from decimals back, not front
Co-authored-by: Péter Szilágyi <peterke@gmail.com>
* all: add thousandths separators for big numbers on log messages
* p2p/sentry: drop accidental file
* common, log: add fast number formatter
* common, eth/protocols/snap: simplifty fancy num types
* log: handle nil big ints