Setting proxy authentication forces that account to be the only current user account

**Describe the bug**
When I sign into the proxy, Batch Explorer uses that user as the current user, and it drops/does not complete signin for the user I need to use to access the batch accounts.

**To Reproduce**
Steps to reproduce the behavior:
1. Fresh installation (no per-user data)
2. Open Batch Explorer
3. Provide the username for the batch accounts
4. Provide the username and password for the proxy
5. Watch Batch Explorer ignore the username provided in step 3 and find that I cannot access the batch accounts I need to see.
6. Flail around in the UI trying to find a place to change the user while preserving the proxy auth.

**Expected behavior**
After navigating the proxy dialog, I expect the authorization flow to continue for the user I supplied in the first auth dialog window.

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Logs(Click profile > View Logs > app.log, client.log)**
[app.log](https://github.com/Azure/BatchExplorer/files/15192761/app.log)
[client.log](https://github.com/Azure/BatchExplorer/files/15192762/client.log)
[python-server.log](https://github.com/Azure/BatchExplorer/files/15192763/python-server.log)

**Version (please complete the following information):**
- OS: Windows]
- Version [2.20.0-stable-966]

Note that both users are in the same tenant. However, I need the two users to be separate. They CANNOT be the same.