Implement project-wise find all references

Find all references currently only works for the currently open file. However, we should look for them project-wise. If indexing is not implemented, it will need to as part of this task.

n.b. We should also implement project-wise rename since the logic should be the same.

Acceptance criteria

• We implement indexing if it's not implemented already.
• We implement project-wise find all references.
• We implement project-wise rename.
• Tests added.