fix(@angular/cli): allow config object to be of JSON.

With this change we allow unset a config value to be a JSON.

Example, `ng config -g schematics {}` will remove the entire `schematics` section from the configuration.

(cherry picked from commit 0a0fc41)

packages/angular/cli/commands/config-impl.ts

@@ -80,7 +80,7 @@ function normalizeValue(value: string | undefined | boolean | number): JsonValue
     return +valueString;
   }
 
-  return value ?? undefined;
+  return parseJson(valueString) ?? value ?? undefined;
 }
 
 export class ConfigCommand extends Command<ConfigCommandSchema> {

tests/legacy-cli/e2e/tests/commands/config/config-set.ts

@@ -15,14 +15,13 @@ export default async function () {
     throw new Error(`Expected "yarn", received "${JSON.stringify(stdout2)}".`);
   }
 
-  await ng('config', 'schematics.@schematics/angular:component.style', 'css');
-  const { stdout: stdout3 } = await ng('config', '@schematics/angular:component.style');
-  if (!stdout2.includes('css')) {
-    throw new Error(`Expected "css", received "${JSON.stringify(stdout3)}".`);
+  await ng('config', 'schematics', '{"@schematics/angular:component":{"style": "scss"}}');
+  const { stdout: stdout3 } = await ng('config', 'schematics.@schematics/angular:component.style');
+  if (!stdout3.includes('scss')) {
+    throw new Error(`Expected "scss", received "${JSON.stringify(stdout3)}".`);
   }
 
-  const { stderr } = await ng('config', 'schematics', 'undefined');
-  if (!stderr.includes('Value cannot be found.')) {
-    throw new Error(`Expected "Value cannot be found", received "${JSON.stringify(stderr)}".`);
-  }
+  await ng('config', 'schematics');
+  await ng('config', 'schematics', 'undefined');
+  await expectToFail(() => ng('config', 'schematics'));
 }