build(aio): improve enum API rendering (#23872)

* The member details section is now called "Members", rather
than "Properties".
* The property table now displays appropriate table headings:
"Member", "Value", "Description".
* The "Value" column is not shown if none of the members have
a value.

Closes #22678

PR Close #23872

aio/tools/transforms/angular-base-package/rendering/hasValues.js

@@ -0,0 +1,9 @@
+module.exports = function hasValues() {
+  return {
+    name: 'hasValues',
+    process: function(list, property) {
+      if (!list || !Array.isArray(list)) return false;
+      return list.some(item => item[property]);
+    }
+  };
+};

aio/tools/transforms/angular-base-package/rendering/hasValues.spec.js

@@ -0,0 +1,19 @@
+const factory = require('./hasValues');
+
+describe('hasValues filter', () => {
+  let filter;
+
+  beforeEach(function() { filter = factory(); });
+
+  it('should be called "hasValues"', function() { expect(filter.name).toEqual('hasValues'); });
+
+  it('should return true if the specified property is truthy on any item in the list', function() {
+    expect(filter.process([], 'a')).toEqual(false);
+    expect(filter.process(0), 'a').toEqual(false);
+    expect(filter.process({}, 'a')).toEqual(false);
+    expect(filter.process([{a: 1}], 'a')).toEqual(true);
+    expect(filter.process([{b: 2}], 'a')).toEqual(false);
+    expect(filter.process([{a: 1, b: 2}], 'a')).toEqual(true);
+    expect(filter.process([{b: 2}, {a: 1}], 'a')).toEqual(true);
+  });
+});