chore: add license header for missing files

[nilsreichardt]

Description

I'm going to split #9702 into two PRs:

1. adding the license header for all missing files (a big PR with many file changes)
2. adding the GitHub Action check for the license header with instructions on adding the license with one command (see ci: add check for license header and add melos command to add & check license header #9704)

I used this command (in the next PR I'm going to add this as a melos command):

addlicense -f header_template.txt --ignore "**/*.yml" --ignore "**/*.yaml" --ignore "**/*.xml" --ignore "**/*.g.dart" --ignore "**/*.sh" --ignore "**/*.html" --ignore "**/*.js" --ignore "**/*.ts" --ignore "**/*.g.h" --ignore "**/*.g.m" --ignore "**/*.rb" --ignore "**/Runner/AppDelegate.swift" --ignore "**/Runner/MainFlutterWindow.swift" --ignore "**/Runner/Runner-Bridging-Header.h" --ignore "**/Runner/AppDelegate.h" --ignore "**/Runner/AppDelegate.m" --ignore "**/Runner/main.m" --ignore "**/MainActivity.kt" --ignore "**/MainActivity.java" --ignore "**/FlutterMultiDexApplication.java" --ignore **/GeneratedPluginRegistrant.swift .

with this in my header_template.txt

Copyright {{.Year}}, the Chromium project authors.  Please see the AUTHORS file
for details. All rights reserved. Use of this source code is governed by a
BSD-style license that can be found in the LICENSE file.

Related Issues

Part of #9702

Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes ([x]).
This will ensure a smooth and quick review process. Updating the pubspec.yaml and changelogs is not required.

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See Contributor Guide).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
• The analyzer (melos run analyze) does not report any problems on my PR.
• I read and followed the Flutter Style Guide.
• I signed the CLA.
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

Does your PR require plugin users to manually update their apps to accommodate your change?

• Yes, this is a breaking change.
• No, this is not a breaking change.

[nilsreichardt]

I have added the missing headers with addlicense.

On which files do we want to add the license headers? I just used the default settings of addlicense but we could use the --ignore parameter.

[nilsreichardt]

On which files do we want to add the license headers? I just used the default settings of addlicense but we could use the --ignore parameter.

Discussed in Slack: We are going to use these ignore flags: --ignore "**/*.yml" --ignore "**/*.yaml" --ignore "**/*.xml" --ignore "**/*.g.dart" --ignore "**/*.sh" --ignore "**/*.html" --ignore "**/*.js" --ignore "**/*.ts" --ignore "**/*.g.h" --ignore "**/*.g.m" --ignore "**/*.rb" --ignore "**/Runner/AppDelegate.swift" --ignore "**/Runner/MainFlutterWindow.swift" --ignore "**/Runner/Runner-Bridging-Header.h" --ignore "**/Runner/AppDelegate.h" --ignore "**/Runner/AppDelegate.m" --ignore "**/Runner/main.m" --ignore "**/MainActivity.kt" --ignore "**/MainActivity.java" --ignore "**/FlutterMultiDexApplication.java" --ignore **/GeneratedPluginRegistrant.swift

[nilsreichardt]

This is the second part: #9704

[Lyokone]

LGTM, there are some conflicts, if you can fix them, I'll try to get that merged quickly :)

[nilsreichardt]

@Lyokone Thanks for the review :) I solved the conflicts 👍