refactor: Add stop_at_height option in ChainstateManager

Remove access to the global gArgs for the stopatheight argument and
replace it by adding a field to the existing ChainstateManager Options
struct.

This should eventually allow users of the ChainstateManager to not rely
on the global gArgs and instead pass in their own options.

src/kernel/chainstatemanager_opts.h

@@ -21,6 +21,7 @@ class CChainParams;
 
 static constexpr bool DEFAULT_CHECKPOINTS_ENABLED{true};
 static constexpr auto DEFAULT_MAX_TIP_AGE{24h};
+static constexpr int DEFAULT_STOPATHEIGHT{0};
 
 namespace kernel {
 
@@ -45,6 +46,7 @@ struct ChainstateManagerOpts {
     DBOptions coins_db{};
     CoinsViewOptions coins_view{};
     Notifications& notifications;
+    int stop_at_height{DEFAULT_STOPATHEIGHT};
 };
 
 } // namespace kernel