test: Add arguments for creating a slimmer setup

Adds more testing options for creating an environment without networking
and a validation interface. This is useful for improving the performance
of the utxo snapshot fuzz test, which constructs a new TestingSetup on
each iteration.

src/test/util/setup_common.h

@@ -52,6 +52,8 @@ struct TestOpts {
     std::vector<const char*> extra_args{};
     bool coins_db_in_memory{true};
     bool block_tree_db_in_memory{true};
+    bool setup_net{true};
+    bool setup_validation_interface{true};
 };
 
 /** Basic testing setup.