[DevTools] Support object destructuring pattern without runtime errors (

facebook#22128)

## Summary

Before this commit, if a hook returned an object and we declared a variable using object destructuring on the returned value, we would produce a runtime error. This was detected via internal testing.

This commit fixes that and adds regression tests.


## Test Plan

- yarn flow
- yarn test
- yarn test-build-devtools
- added new regression tests 
- named hooks still work on manual test of browser extension on a few different apps (code sandbox, create-react-app, internally).

packages/react-devtools-extensions/src/SourceMapMetadataConsumer.js

@@ -89,9 +89,9 @@ export class SourceMapMetadataConsumer {
     return getHookNameForLocation({line, column}, hookMap);
   }
 
-  hasHookMap(source: ?string) {
+  hasHookMap(source: ?string): boolean {
     if (source == null) {
-      return null;
+      return false;
     }
     return this._getHookMapForSource(source) != null;
   }

packages/react-devtools-extensions/src/__tests__/__source__/ComponentWithCustomHook.js

@@ -7,11 +7,12 @@
  * @flow
  */
 
-import React, {useEffect, useState} from 'react';
+import React, {useDebugValue, useEffect, useState} from 'react';
 
 export function Component() {
   const [count, setCount] = useState(0);
   const isDarkMode = useIsDarkMode();
+  const {foo} = useFoo();
 
   useEffect(() => {
     // ...
@@ -23,6 +24,7 @@ export function Component() {
     <>
       <div>Dark mode? {isDarkMode}</div>
       <div>Count: {count}</div>
+      <div>Foo: {foo}</div>
       <button onClick={handleClick}>Update count</button>
     </>
   );
@@ -37,3 +39,8 @@ function useIsDarkMode() {
 
   return isDarkMode;
 }
+
+function useFoo() {
+  useDebugValue('foo');
+  return {foo: true};
+}