pip keyring entries should be pip-specific

Currently pip stores in keyring using:

{
    "application": "Python keyring library",
    "service": "domain_name", 
    "username": "my_username",
    "label": f"Password for '{my_username}' on '{domain_name}'",
}

If another entry already exists for domain_name, it will overwrite or use that.

We can have separate auth creds for a pip repo. But the current style overwrites it.

We must sufficiently separate the cred partition for pip.

For example, we can:

1. Prepend pip: to service.
2. Store entire repo link instead of just the domain name.