Rename ValueGraph to Graph

[fortmarek]

Short description 📝

Since ValueGraph has been for some time the only graph, I think we can drop the Value suffix

Checklist ✅

• The code architecture and patterns are consistent with the rest of the codebase.
• The changes have been tested following the documented guidelines.
• The CHANGELOG.md has been updated to reflect the changes. In case of a breaking change, it's been flagged as such.
• In case the PR introduces changes that affect users, the documentation has been updated.

[kwridan]

Thanks @fortmarek, this should reduce some of the confusion around the graph type 😅