Add tests for bridging AgentContext wrappers

[trask]

#3869 introduced support for bridging AgentContext wrappers, it would be great to add tests for these (adding AgentContext wrappers on both sides of the bridge, e.g. user AgentContext wrappers and javaagent extension AgentContext wrappers).

[trask]

Closing, I believe there are tests that cover this now.