Backport upstream PRs that remove Boost usage #4819
Description
The PRs we are missing, in merged-to-upstream order:
- refactor: Replace boost::bind with std::bind bitcoin/bitcoin#13743
- rpc: Remove unused boost::this_thread::interruption_point bitcoin/bitcoin#17382
- move-only: move coins statistics utils out of RPC bitcoin/bitcoin#16728
- wallet: Remove unused boost::this_thread::interruption_point bitcoin/bitcoin#17405
- refactor: Replace boost::mutex,condition_var,chrono with std equivalents in scheduler bitcoin/bitcoin#18234
- refactor: drop boost::signals2 in validationinterface bitcoin/bitcoin#18524
- test: Replace boost::mutex with std::mutex bitcoin/bitcoin#18695
- wallet: Remove boost from PeriodicFlush bitcoin/bitcoin#18792
- validation: Make VerifyDB level 4 interruptible bitcoin/bitcoin#19142
- Remove unused boost/thread bitcoin/bitcoin#18758
- init: use std::thread for ThreadImport() bitcoin/bitcoin#19197
- refactor: Misc scheduler cleanups bitcoin/bitcoin#19090