Allow `Union[str, AuthApiKey, AuthOIDCxxx, ...]` as `auth_credentials` inputs in connection helper functions

[databyjp]

Propose connect_to_xx functions to optionally, take the Weaviate API key as strings

So

client = weaviate.connect_to_wcs(
    cluster_url="wcs-url-here",
    auth_credentials=weaviate.auth.AuthApiKey("key-here"),
)

Could also be:

client = weaviate.connect_to_wcs(
    cluster_url="wcs-url-here",
    auth_credentials="key-here",
)

This would be also applicable to connect_to_local also.