lint: Remove unused rules

We picked those up from Polari, which had those for

 - object arrays:
    let foo = [
        { bar: 42,
          quz: true },
        { bar: 23,
          quz: false }
    ];

 - "enums":

    let Options = {
        ONE:   0,
        TWO:   1,
        THREE: 2
    };

We don't have either of those, so drop the rules to minimise divergence
with gjs.

https://gitlab.gnome.org/GNOME/gnome-shell-extensions/merge_requests/57

lint/eslintrc-shell.json

@@ -20,21 +20,12 @@
             4,
             {
                 "ignoredNodes": [
-                    "ArrayExpression > ObjectExpression",
                     "CallExpression[callee.object.name=GObject][callee.property.name=registerClass] > ClassExpression:first-child",
                     "ConditionalExpression"
                 ],
                 "MemberExpression": "off"
             }
         ],
-        "key-spacing": [
-            "error",
-            {
-                "mode": "minimum",
-                "beforeColon": false,
-                "afterColon": true
-            }
-        ],
         "no-restricted-properties": [
             "error",
             {