Allow extended testcase tags to be applicable to other agent initialisation types

[coolmule0]

So far additional testcase tags work for the <agent> tags, but do not work for other types of agent-initialisation, like <agent_region> tag.

It involves ensuring the <bag> and <sdradius> tags are parsing for also agentEmitter and AgentRegion.

[coolmule0]

Not currently important for RateSetter related work, but breaks the functionality of some of the SteerSuite testcases