refactor: Do not discard `try_lock()` return value
refactor: Do not discard `try_lock()` return value

Microsoft's C++ Standard Library uses the `[[nodiscard]]` attribute for
`try_lock()`.
See: https://github.com/microsoft/STL/blob/main/stl/inc/mutex

This change allows to drop the current suppression for the warning C4838
and helps to prevent the upcoming warning C4858.
See: https://github.com/microsoft/STL/commit/539c26c923b38cd0b5eba2bb11de4bea9d5c6e43

ajtowns/bitcoin,bitcoinsSG/bitcoin,bitcoinsSG/bitcoin,fanquake/bitcoin,bitcoin/bitcoin,tecnovert/particl-core,namecoin/namecoin-core,jambolo/bitcoin,AkioNak/bitcoin,kallewoof/bitcoin,lateminer/bitcoin,fanquake/bitcoin,AkioNak/bitcoin,namecoin/namecoin-core,lateminer/bitcoin,sipsorcery/bitcoin,sstone/bitcoin,namecoin/namecoin-core,bitcoin/bitcoin,jambolo/bitcoin,bitcoinsSG/bitcoin,sipsorcery/bitcoin,tecnovert/particl-core,lateminer/bitcoin,bitcoinsSG/bitcoin,fanquake/bitcoin,mruddy/bitcoin,kallewoof/bitcoin,sipsorcery/bitcoin,ajtowns/bitcoin,jambolo/bitcoin,fanquake/bitcoin,particl/particl-core,bitcoin/bitcoin,tecnovert/particl-core,kallewoof/bitcoin,namecoin/namecoin-core,ajtowns/bitcoin,kallewoof/bitcoin,sipsorcery/bitcoin,ajtowns/bitcoin,AkioNak/bitcoin,particl/particl-core,jambolo/bitcoin,tecnovert/particl-core,particl/particl-core,mruddy/bitcoin,jambolo/bitcoin,lateminer/bitcoin,kallewoof/bitcoin,sstone/bitcoin,sstone/bitcoin,tecnovert/particl-core,sipsorcery/bitcoin,AkioNak/bitcoin,particl/particl-core,AkioNak/bitcoin,bitcoin/bitcoin,particl/particl-core,tecnovert/particl-core,lateminer/bitcoin,sstone/bitcoin,lateminer/bitcoin,sstone/bitcoin,namecoin/namecoin-core,sipsorcery/bitcoin,AkioNak/bitcoin,fanquake/bitcoin,ajtowns/bitcoin,bitcoin/bitcoin,mruddy/bitcoin,bitcoinsSG/bitcoin,kallewoof/bitcoin,bitcoin/bitcoin,mruddy/bitcoin,bitcoinsSG/bitcoin,mruddy/bitcoin,jambolo/bitcoin,namecoin/namecoin-core,sstone/bitcoin,fanquake/bitcoin,particl/particl-core,mruddy/bitcoin,ajtowns/bitcoin