misc: adopt minimal license headers

[paulirish]

We're allowed to have more minimal license headers.

• https://opensource.google/documentation/reference/releasing/preparing#license-headers
• https://opensource.google/documentation/reference/copyright
• go/releasing/preparing#spdx
• go/simpler-js-notices
• https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/c++.md#file-headers

So, let's!

---

Also... in #10469 we added an AUTHORS file and changed to 'The Lighthouse Authors'. The policy says:

However for projects that accept a great deal of external code (such as Chromium), you may wish to optionally update the copyright statements in your source code to "Copyright 2014 The [Project] Authors" to acknowledge the community's efforts.

We haven't added a name to this since the file was established. So I'd prefer we just stick to the basic model (drop the AUTHORS file, tweak copyright assignment). This PR also includes that change.

---

FYI The diff page is pretty rough on the browser. Spoiler alert.. It's a lot of diffs like this:

diff --git a/core/index.js b/core/index.js
index a6d77f3c5..26864ef42 100644
--- a/core/index.js
+++ b/core/index.js
@@ -1,7 +1,7 @@
 /**
- * @license Copyright 2016 The Lighthouse Authors. All Rights Reserved.
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
- * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
+ * @license
+ * Copyright 2016 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 import Trace from './gather/gatherers/trace.js';

[adamraine]

Looks like smokes are broke, did decreasing the size of the license affect our transfer size expectations?

[connorjclark]

Changing the source file comments is fine, but the bundle is a form of distribution so it should retain the full reference to the license IMO.

[paulirish]

based on my read of the above docs, the minimal header would be fine for a bundle. but... i don't care too much. i'm happy to keep the full text version for this case. :)

[connorjclark]

I suppose the "SPDX-License-Identifier" thing there is pretty cut and dry in terms of declaring the license that applies (tho, it's for a robot, not a human). Still, I think it's nice to give the whole shebang for the bundle

[connorjclark]

lol we both thought this was the bundle comment header, but that's something else and less verbose. nvm

[paulirish]

did decreasing the size of the license affect our transfer size expectations?

yup. 😢

[connorjclark]

So I'd prefer we just stick to the basic model (drop the AUTHORS file, tweak copyright assignment)

nitting on your wording: this PR changes the acknowledgement of the copyright found in source headers, but that's a meaningless change wrt. to actual copyright assignment. Contributors have and will continue to retain their copyrights... and we are just choosing a different valid approach for legalese comment cruft that is within the guidelines set by our employer