f9fdcec7e9 settings: Add resetSettings() method (Ryan Ofsky)
77fabffef4 init: Remove Shutdown() node.args reset (Ryan Ofsky)
0e55bc6e7f settings: Add update/getPersistent/isIgnored methods (Ryan Ofsky)
Pull request description:
Add `interfaces::Node` `updateSetting`, `forceSetting`, `resetSettings`, `isSettingIgnored`, and `getPersistentSetting` methods so GUI is able to manipulate `settings.json` file and use and modify node settings.
(Originally this PR also contained GUI changes to unify bitcoin-qt and bitcoind persistent settings and call these methods, but the GUI commits have been dropped from this PR and moved to bitcoin-core/gui/pull/602)
ACKs for top commit:
vasild:
ACK f9fdcec7e9
hebasto:
re-ACK f9fdcec7e9, only a function renamed since my recent [review](https://github.com/bitcoin/bitcoin/pull/15936#pullrequestreview-979324357).
Tree-SHA512: 4cac853ee29be96d2ff38404165b9dfb7c622b2a9c99a15979596f3484ffde0da3d9c9c372677dff5119ca7cffa6383d81037fd9889a29cc9285882a8dc0c268