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"

I've split the work in multiple commits:

• 4c32192: setup a new empty project.
• 1666d3e: add and use the first code snippet.
• 989868a: enable Dependabot on the snippets project.
• 6b58402: add a new workflow to validate the snippets project.
• e8d17e9: add documentation about the snippets project.

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?

[utzcoz]

@MGaetan89 Maybe it is ready for merging?

[MGaetan89]

@MGaetan89 Maybe it is ready for merging?

I wanted to add some documentation and update Dependabot first. I'll do it in a bit

[MGaetan89]

The PR should be complete now.

I've added the following commits:

• 989868a: enable Dependabot on the snippets project. Now we will get one PR for all GitHub Actions, one PR for all Gradle dependencies, and one PR for each Python dependency.
• 6b58402: add a new workflow to validate the snippets project (check code style, build, lint, and test the project).
• e8d17e9: add documentation about the snippets project.

[utzcoz]

LGTM.