Add AI policy to contribution guidelines and PR template

The amount of AI generated PRs is increasing while their quality often remains poor. The introduced guidelines aim to reduce the number of poor quality AI PRs while simultaneously increasing the quality of high quality AI PRs.

New checkboxes for compliance with the AI policy and to increase the PR quality are introduced to the PR template.

Author: TobiGr

.github/CONTRIBUTING.md

@@ -42,6 +42,17 @@ You'll see *exactly* what is sent, be able to add **your comments**, and then se
 * Create PRs that cover only **one specific issue/solution/bug**. Do not create PRs that are huge monoliths and could have been split into multiple independent contributions.
 * NewPipe uses [NewPipeExtractor](https://github.com/TeamNewPipe/NewPipeExtractor) to fetch data from services. If you need to change something there, you must test your changes in NewPipe. Telling NewPipe to use your extractor version can be accomplished by editing the `app/build.gradle` file: the comments under the "NewPipe libraries" section of `dependencies` will help you out.
 
+### Use of generative AI
+
+* Using generative AI to develop new features or making larger code changes is generally prohibited. Please refrain from contributions which are heavily depending on AI generated source code because they are usually lacking a fundamental understanding of the overall project structure and thus come with poor quality. However, you are allowed to use gen. AI if you
+  * are aware of the project structure,
+  * ensure that the generated code follows the project structure,
+  * fully understand the generated code, and
+  * review the generated code completely.
+* Using AI to find the root cause of bugs and generating small fixes might be acceptable. However, gen. AI often does not fix the underlying problem but is trying to fix the symptoms. If you are using AI to fix bugs, ensure that the root cause is tackled.
+* The use of AI to generate documentation is allowed. We ask you to thoroughly check the quality of generated documentation – wrong, misleading or uninformative documentation is useless and wastes the reader's time. Ensure that reasoning is documented.
+* PRs that do not follow the AI policy can be closed without further explanation.
+
 ### Creating a Pull Request (PR)
 
 * Make changes on a **separate branch** with a meaningful name, not on the _master_ branch or the _dev_ branch. This is commonly known as *feature branch workflow*. You may then send your changes as a pull request (PR) on GitHub.

.github/PULL_REQUEST_TEMPLATE.md

@@ -32,3 +32,5 @@ The APK can be found by going to the "Checks" tab below the title. On the left p
 
 #### Due diligence
 - [ ] I read the [contribution guidelines](https://github.com/TeamNewPipe/NewPipe/blob/HEAD/.github/CONTRIBUTING.md).
+- [ ] The proposed changes follow the [AI policy](https://github.com/TeamNewPipe/NewPipe/blob/HEAD/.github/CONTRIBUTING.md#use-of-generative-ai).
+- [ ] I tested the changes using an emulator or a physical device.