> validation: replace ::Params() calls with chainstate/chainman member
> refactor: Replace Chainstate::m_params with chainman.GetParams()
> kernel: pass params to BlockManager rather than using a global
After these 3 commits, there is no more validation code using the global getter for the global CChainParams.
The chainparams are now accessed either:
- via a `Config` passed as a function argument
- via `ChainstateManager::GetParams` (uses `ChainstateManager::m_config::GetChainParams()`)
- a chainparams function argument
This is a backport of core#25264, core#25830, core#24595