Add optional-chaining and nullish-coalescing to preset-env (#10811)

* Add support for optional-chaining (stage 4) in present-env

* revert babel-preset-env built-in-modules.json

* add shipped proposal syntax map entry, optional chaining

* update remaining syntax plugin references, proposal description

* Add support for nullish coalescing operator in preset-env

* selectively enable sort-keys rule

* enforce sort-keys on shipped-proposals

* don't use Object.entries()

* Update fixtures

packages/babel-compat-data/data/plugins.json

@@ -299,6 +299,10 @@
     "opera": "53",
     "electron": "3.1"
   },
+  "proposal-optional-chaining": {
+    "chrome": "80",
+    "opera": "67"
+  },
   "transform-named-capturing-groups-regex": {
     "chrome": "64",
     "safari": "11.1",
@@ -349,5 +353,10 @@
     "phantom": "2",
     "samsung": "2.1",
     "electron": "0.2"
+  },
+  "proposal-nullish-coalescing-operator": {
+    "chrome": "80",
+    "firefox": "72",
+    "opera": "67"
   }
 }