Cannot use explorer with emulator when started with custom key

When you start the Cosmos DB Emulator with a custom key using the `/Key` or `/KeyFile` [command line parameters](https://docs.microsoft.com/en-us/azure/cosmos-db/emulator-command-line-parameters) it seems impossible to use the Explorer as it has no way to provide the key to use. It defaults to the built-in key.

I am running the emulator on my host machine and am developing my application in a Docker container. Therefore I need to enable network access on the emulator, which requires a custom key to be provided. I can successfully connect from the container to the emulator on the host using the generated key, however I am not able to inspect the data using the Explorer on the host.

No files or tests are named in the issue. Start by tracing how Explorer authenticates to the Cosmos DB Emulator and where the built-in key is selected; then identify the existing connection or key-entry path. Done means Explorer can use a custom key supplied through /Key or /KeyFile and inspect emulator data.

Written by the indexing model from the issue text.