Update OpenStack Swift scaler

The swiftURL is now optional since it can be retrieved from the catalog.
The optional parameter regionName was added.

Signed-off-by: Pedro Felipe Dominguite <p.dominguite@sidi.org.br>

* Update Keystone helper

Now, the Keystone module can retrieve the service URL dynamically for any OpenStack service, by searching into the OpenStack catalog within the given authorization scope.

Signed-off-by: Pedro Felipe Dominguite <p.dominguite@sidi.org.br>

* Add serviceTypes util

This helper retrieves all the service types historically used by an OpenStack project.

Signed-off-by: Pedro Felipe Dominguite <p.dominguite@sidi.org.br>

* Add OpenStack region option

It specifies the region name where the service is available.
It can be used to retrieve the correct service URL from the catalog.

Signed-off-by: Pedro Felipe Dominguite <p.dominguite@sidi.org.br>

* Update OpenStack Swift scaler unit tests

Signed-off-by: Pedro Felipe Dominguite <p.dominguite@sidi.org.br>

* Update CHANGELOG.md

Signed-off-by: Pedro Felipe Dominguite <p.dominguite@sidi.org.br>

CHANGELOG.md

@@ -34,6 +34,7 @@
 - Fix memory leak by checking triggers uniqueness properly ([#1640](https://github.com/kedacore/keda/pull/1640))
 - Print correct ScaleTarget Kind in Events ([#1641](https://github.com/kedacore/keda/pull/1641))
 - Fixed keda clusterroles to give permissions for clustertriggerauthentications ([#1645](https://github.com/kedacore/keda/pull/1645))
+- Make `swiftURL` parameter optional for the OpenStack Swift scaler ([#1652](https://github.com/kedacore/keda/pull/1652))
 
 ### Breaking Changes