App Should Be QR Tool, Not QR Vault

Based on the PR in process (https://github.com/BlockchainCommons/GordianQRTool-iOS/pull/60), the app is being called "QR Vault" at a deep level, including entitlements, the project file, UI Tests, and perhaps most notably, the name of the cloud container. We want to update this to "QR Tool" as much as possible, especially for anything like the cloud container that could have user impact.