When running the tests that can be executed either on server or client
context, without defining 'ipa_context', the context is automatically
identified.
Currently, the tests in upstream CI run only on a server, and the
context is identified as "server" context, and in order to run the test
using a client context 'ipa_context' must be set to 'client'.
This patch fixes all the client context tests by correctly setting
ipa_context when running the client context tests in a server host.
Update trust README file and add tests for executing plugin with
`ipaapi_context` set to `client`.
A new test playbook can be found at:
tests/trust/test_trust_client_context.yml
The new test file can be executed in a FreeIPA client host that is
not a server. In this case, it should be defined in the `ipaclients`
group, in the inventory file.
