Add `include_personal` argument to contributed projects GraphQL query

What does this MR do and why?

Need for &13066 (closed). We are adding a Contributed tab to Your work -> Projects and we want to show personal projects in this tab but currently the contributed projects GraphQL query filters personal projects out. This MR adds a include_personal argument to the GraphQL query. The new argument defaults to false so the existing behavior is preserved and this is not a breaking change.

MR acceptance checklist

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How to set up and validate locally

1. Go to http://gdk.test:3000/projects/new#blank_project
2. Choose your namespace from the Pick a group or namespace dropodown
3. Make sure the Initialize repository with a README checkbox is checked
4. Go to http://gdk.test:3000/-/graphql-explorer
5. Run the following query:

query getProjects {
  currentUser {
    contributedProjects(includePersonal: true) {
      nodes {
        nameWithNamespace
      }
    }
  }
}