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/ledger/View_test.cpp

@@ -844,7 +844,7 @@ class DirIsEmpty_test
         auto const alice = Account("alice");
         auto const bogie = Account("bogie");
 
-        Env env(*this, features(featureMultiSign));
+        Env env(*this, with_features(featureMultiSign));
 
         env.fund(XRP(10000), alice);
         env.close();