[SC-786] Post-Merge Fixes

[marvinkruse]

Just noticed two things when checking #662 after it was merged, which is why I opened this PR quickly. It had:

• Compiler Warnings
  • In the main contract, _token was shadowing _token, so I renamed it according to our new dev guidelines
• Naming of AccessMock
  • File was called ContractName_AccessMock.sol instead of ContractName_Exposed.sol
  • File was in the wrong folder (not in the same one as the test file)

[linear[bot]]

SC-786 Story: Add fee collection to DepositVault contract

[Zitzak]

I think the PR was actually created before we finished our dev guidelines and due to no additional reviewers, and needing the changes added in the PR to the FM base I moved forward to merging it. Thank you for changing it @marvinkruse