RPC/Client: test used and paid storage space services/commands

Context

Closes #3676 (closed).

Add a test for the newly added RPC and CLI to request the used and paid storage spaces of a contract.

Manually testing the MR

dune exec tezt/tests/main.exe -- --file used_paid_storage_spaces.ml

Checklist

• Provide automatic testing (see the testing guide).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR