Refactor EnumerableSet generation and tests (#4762)

scripts/generate/templates/EnumerableSet.opts.js

@@ -0,0 +1,10 @@
+const mapType = str => (str == 'uint256' ? 'Uint' : `${str.charAt(0).toUpperCase()}${str.slice(1)}`);
+
+const formatType = type => ({
+  name: `${mapType(type)}Set`,
+  type,
+});
+
+const TYPES = ['bytes32', 'address', 'uint256'].map(formatType);
+
+module.exports = { TYPES, formatType };