DefaultHostURLTemplate should construct URLs with realmDomainComponent

[scellef]

Hello!

The DefaultHostURLTemplate currently constructs URLs using two parameter sub-domains ahead of the oraclecloud.com domain component. However, numerous Oracle Cloud regions use different domain components, such as:

    {
        "regionKey": "doh",
        "realmKey": "oc21",
        "regionIdentifier": "me-dcc-doha-1",
        "realmDomainComponent": "oraclecloud21.com"
    },

Ideally this or a different variable could be provided that would parameterize the realm domain component so client applications can accommodate all available regions.

[mricken]

That is the default domain if a region is not known and no other realm has been specified.

Please see https://docs.oracle.com/en-us/iaas/Content/API/Concepts/sdk_adding_new_region_endpoints.htm for how to add regions in realms other than OC1.