Change features default behavior in Env (RIPD-1460):

Enable all supported amendments in Env by default. Rename `features()`
to `with_features()` and add `all_features_except()` to support feature
subsets in Env. Refactor internal feature handling based on a bitset.

src/test/rpc/LedgerClosed_test.cpp

@@ -30,7 +30,7 @@ public:
     void testMonitorRoot()
     {
         using namespace test::jtx;
-        Env env {*this};
+        Env env {*this, no_features};
         Account const alice {"alice"};
         env.fund(XRP(10000), alice);