Merge #21525: [Bundle 4.5/n] Followup fixups to bundle 4

693414d271 node/ifaces: ChainImpl: Use an accessor for ChainMan (Carl Dong)
98c4e252f0 node/ifaces: NodeImpl: Use an accessor for ChainMan (Carl Dong)
7e8b5ee814 validation: Make BlockManager::LookupBlockIndex const (Carl Dong)
88aead263c node: Avoid potential UB by asserting assumptions (Carl Dong)
1dd8ed7a84 net_processing: Move comments to declarations (Carl Dong)
07156eb387 node/coinstats: Replace #include with fwd-declaration (Carl Dong)
7b8e976cd5 miner: Add chainstate member to BlockAssembler (Carl Dong)
e62067e7bc Revert "miner: Pass in chainstate to BlockAssembler::CreateNewBlock" (Carl Dong)
eede0647b0 Revert "scripted-diff: Invoke CreateNewBlock with chainstate" (Carl Dong)
0c1b2bc549 Revert "miner: Remove old CreateNewBlock w/o chainstate param" (Carl Dong)

Pull request description:

  Chronological history of this changeset:
  1. Bundle 4 (#21270) got merged
  2. Posthumous reviews were posted
  3. These changes were prepended in bundle 5
  4. More reviews were added in bundle 5
  5. Someone suggested that we split the prepended changes up to another PR
  6. This is that PR

  In the future, I will just do posthumous review changes in another PR instead. I apologize for the confusion.

  Addresses posthumous reviews on bundle 4:
    - From jnewbery:
      - https://github.com/bitcoin/bitcoin/pull/21270#issuecomment-796738048
        - I didn't fix this one, but I added a `TODO` comment so that we don't lost track of it
      - https://github.com/bitcoin/bitcoin/pull/21270#discussion_r592291225
      - https://github.com/bitcoin/bitcoin/pull/21270#discussion_r592296942
      - https://github.com/bitcoin/bitcoin/pull/21270#discussion_r592299738
      - https://github.com/bitcoin/bitcoin/pull/21270#discussion_r592301704
    - From MarcoFalke:
      - https://github.com/bitcoin/bitcoin/pull/21270#discussion_r593096212
      - https://github.com/bitcoin/bitcoin/pull/21270#discussion_r593097032
      - https://github.com/bitcoin/bitcoin/pull/21270#discussion_r593097867
      - https://github.com/bitcoin/bitcoin/pull/21270#discussion_r593100570

  Addresses reviews on bundle 5:
  - Checking chainman existence before locking cs_main
    - MarcoFalke
      - https://github.com/bitcoin/bitcoin/pull/21391#discussion_r596601776
      - https://github.com/bitcoin/bitcoin/pull/21391#discussion_r596601876
  - Appropriate locking, usage of chainman, and control flow in `src/node/interfaces.cpp`
    - MarcoFalke
      - https://github.com/bitcoin/bitcoin/pull/21391#discussion_r596601383
    - jnewbery
      - https://github.com/bitcoin/bitcoin/pull/21391#discussion_r597029360
      - https://github.com/bitcoin/bitcoin/pull/21391#discussion_r597029921
    - ryanofsky
      - https://github.com/bitcoin/bitcoin/pull/21391#discussion_r597163828
  - Style/comment formatting changes
    - jnewbery
      - https://github.com/bitcoin/bitcoin/pull/21391#discussion_r597026552
      - https://github.com/bitcoin/bitcoin/pull/21391#discussion_r597027186
  - Making LookupBlockIndex const
    - jnewbery
      - https://github.com/bitcoin/bitcoin/pull/21391#discussion_r597035062

ACKs for top commit:
  MarcoFalke:
    review ACK 693414d271 🛐
  ryanofsky:
    Code review ACK 693414d271. I reviewed this previously as part of #21391. I am a fan of the increasingly complicated bundle numbering, and kind of hope there in the next round there is some way we can get bundles 5.333333 and 5.666667!
  jamesob:
    ACK 693414d271 ([`jamesob/ackr/21525.1.dongcarl.bundle_4_5_n_followup_f`](https://github.com/jamesob/bitcoin/tree/ackr/21525.1.dongcarl.bundle_4_5_n_followup_f))

Tree-SHA512: 9bdc199f70400d01764e1bd03c25bdb6cff26dcef60e4ca3b649baf8d017a2dfc1f058099067962b4b6ccd32d078002b1389d733039f4c337558cb70324c0ee3

src/test/util/setup_common.cpp

@@ -247,7 +247,7 @@ CBlock TestChain100Setup::CreateAndProcessBlock(const std::vector<CMutableTransa
 {
     const CChainParams& chainparams = Params();
     CTxMemPool empty_pool;
-    CBlock block = BlockAssembler(empty_pool, chainparams).CreateNewBlock(::ChainstateActive(), scriptPubKey)->block;
+    CBlock block = BlockAssembler(::ChainstateActive(), empty_pool, chainparams).CreateNewBlock(scriptPubKey)->block;
 
     Assert(block.vtx.size() == 1);
     for (const CMutableTransaction& tx : txns) {