Contexts update + buffer flushing + cleanup (#338)

* Update lib/rocprofiler-sdk/context/context.*

- get_registered_contexts functions (local copy)

* Update lib/rocprofiler-sdk/hsa/{queue,queue_controller}.cpp

- remove ROCPROFILER_BUFFER_TRACING_MEMORY_COPY code

* Update tests/kernel-tracing/kernel-tracing.cpp

- move stop() and flush() in tool_fini to before reporting of sizes of data collected

* Update lib/rocprofiler-sdk/hsa/hsa.*

- remove stale set_callback / activity_functor_t code

* Update lib/rocprofiler-sdk/buffer.cpp

- full wait instead of returning busy when buffer is busy
- use task_group::join instead of task_group::wait to fully wait for tasks to finish (bug fix)

* Update lib/rocprofiler-sdk/agent.cpp

- support agent mapping for CPU agents

* Remove direct access to vector of registered contexts

source/lib/rocprofiler-sdk/counters/core.hpp

@@ -103,9 +103,9 @@ configure_buffered_dispatch(rocprofiler_context_id_t                         con
                             void*                                            callback_args);
 
 void
-start_context(context::context*);
+start_context(const context::context*);
 
 void
-stop_context(context::context*);
+stop_context(const context::context*);
 }  // namespace counters
 }  // namespace rocprofiler