081accb875 Pass chain locked variables where needed (Russell Yanofsky)
79d579f4e1 Remove uses of cs_main in wallet code (Russell Yanofsky)
ea961c3d72 Remove direct node->wallet calls in init.cpp (Russell Yanofsky)
8db11dd0b1 Pass chain and client variables where needed (Russell Yanofsky)
7e2e62cf7c Add skeleton chain and client classes (Russell Yanofsky)
Pull request description:
This creates an incomplete [`Chain`](https://github.com/ryanofsky/bitcoin/blob/pr/wipc-sep/src/interfaces/chain.h) interface in [`src/interfaces/`](https://github.com/ryanofsky/bitcoin/tree/pr/wipc-sep/src/interfaces) and begins to update wallet code to use it.
#10973 builds on this, changing the wallet to use the new interface to access chain state, instead of using CBlockIndex pointers and global variables like `chainActive`.
Tree-SHA512: 6ef05a4d8ebf57f2ad71835e4d970c9c59e34057e39e48cee76b887492c2fee907e3f6a74a9861e5a9f97cdc6823f4865ebc41ec556ab371ebca1b664c20dbea