Add create/delete context operations to the AxonServerContainer

[smcvb]

Feature Description

It would be beneficial if the AxonServerContainer contained a create and delete context operation.
Having these would simplify multi-node Axon Server test cases where a custom context is desired.
The following pointers come to mind for this feature:

1. Validate whether we're dealing with a multi-node Axon Server setup, as otherwise contexts cannot be created.
2. Operation to select the replication group should be present.

Current Behaviour

There is no provided create/delete operation on the AxonServerContainer.
As such, users are inclined to deal with the AxonServerConnectionManager in their test case themselves to achieve context construction.

Wanted Behaviour

The AxonServerContainer provides an operation to create and delete contexts.

Possible Workarounds

Users can utilize the AxonServerConnectionManager in their test case to access the ControlChannel for context creation/deletion.