Add US tenant configuration options

[virtualroot]

User Story
As a User
I want to be able to reach the US tenant without an environment variable
So that it's the default option after setting it up

Behaviors:

CLI flag

$ deepset-cloud --tenant us upload ./examples/data # To override the default tenant only

configuration file

$ deepset-cloud configure set tenant us # US tenant becomes the default
cat ~/.config/deepset-cloud/config.toml
tenant = us
$ deepset-cloud upload ./examples/data

SDK

from deepset_cloud_sdk.workflows.sync_client.files import upload
from deepset_cloud_sdk.config import initialize

options = {
    "tenant": "us",
    "api_key": "<foobar>",
}

initialize(**options)

upload(
	...
)