Create a new snippets project for Java

[MGaetan89]

This PR creates a new snippets Android project that uses Java.
The goal of that project is to contain all the code snippets from robolectric.org. This will allow us to compile them and ensure a coherent code style.

To create/use a snippet:

• Surround the interesting piece of code with:

// --8<-- [start:some_identifier]
class MyFancyJavaCode {}
// --8<-- [start:some_identifier]

• Include it in your Markdown file with:

--8<-- "snippets/<path_to_your_file>:some_identifier"

Note

This PR is currently in draft to gather feedback regarding this approach before going any further with it.
The first commit (4c32192) focuses on creating a new empty project. There's nothing fancy there.
The second one (1666d3e) integrates the Java snippet from Robolectric's homepage.

If this solution is fine for you, before merging this PR, I'll add the following to it:

• An update to the main Readme file to explain how snippets work.
• A Readme file in the snippets project explaining its goal.
• A new GitHub Actions to:
  • Check the code style of the snippets project.
  • Compile and test the snippets project.
• Enable Dependabot for Gradle.

Once this PR is approved and merged, the next steps are:

• Include all the other Java snippets from the website in this project.
• Create a new kotlin module and include all the Kotlin snippets in it.
• Include all the Groovy/Kotlin DSL snippets.

[utzcoz]

@MGaetan89 I am afraid of these code snippet becomes oudated very soon. I prefer to using snippet in Robolectric repository or previous other repository.

[MGaetan89]

@MGaetan89 I am afraid of these code snippet becomes oudated very soon. I prefer to using snippet in Robolectric repository or previous other repository.

Not sure to understand your point.
Currently, these snippets are hardcoded inside each page and probably haven't changed in a long time. This would ensure that they are always working will the latest version of Robolectric.
Or are you suggesting to move them inside the robolectric/robolectric repository?