Merge bitcoin/bitcoin#30200: Introduce Mining interface

a9716c53f0 rpc: call IsInitialBlockDownload via miner interface (Sjors Provoost)
dda0b0834f rpc: minize getTipHash() calls in gbt (Sjors Provoost)
7b4d3249ce rpc: call processNewBlock via miner interface (Sjors Provoost)
9e228351e7 rpc: getTransactionsUpdated via miner interface (Sjors Provoost)
64ebb0f971 Always pass options to BlockAssembler constructor (Sjors Provoost)
4bf2e361da rpc: call CreateNewBlock via miner interface (Sjors Provoost)
404b01c436 rpc: getblocktemplate getTipHash() via Miner interface (Sjors Provoost)
d8a3496b5a rpc: call TestBlockValidity via miner interface (Sjors Provoost)
8ecb681678 Introduce Mining interface (Sjors Provoost)

Pull request description:

  Introduce a `Mining` interface for the `getblocktemplate`, `generateblock` and other mining RPCs to use now, and for Stratum v2 to use later.

  Suggested here: https://github.com/bitcoin/bitcoin/pull/29346#issuecomment-2108528652

  The selection of methods added to the interface is mostly based on what the Template Provider in #29432 uses. It could be expanded further so that `rpc/mining.cpp` no longer needs `EnsureMemPool` and `EnsureChainman`.

  This PR should be a pure refactor.

ACKs for top commit:
  tdb3:
    re ACK a9716c53f0
  itornaza:
    Code review and std-tests ACK a9716c53f0
  ryanofsky:
    Code review ACK a9716c53f0 with one minor suggestion in case you update. Only changes since last review were other small changes to the interface.

Tree-SHA512: cf97f87d6e9ed89da3835a0730da3b24a7b14c8605ea221149103a5915e79598cf082a95f2bc88e33f1c450e3d4aad88aed1163a29195acca88bcace055af724

src/init.cpp

@@ -31,6 +31,7 @@
 #include <init/common.h>
 #include <interfaces/chain.h>
 #include <interfaces/init.h>
+#include <interfaces/mining.h>
 #include <interfaces/node.h>
 #include <kernel/context.h>
 #include <key.h>
@@ -1117,6 +1118,7 @@ bool AppInitLockDataDirectory()
 bool AppInitInterfaces(NodeContext& node)
 {
     node.chain = node.init->makeChain();
+    node.mining = node.init->makeMining();
     return true;
 }