Guest-components only support the `resource` plugin, no other plugins are supported

[salmanyam]

Due to the hardcode plugin name (i.e., resource) for get_resource in kbs_protocol of attestation-agent in guest-components, only the resource plugin in trustee is invocable. The following lines of code show the hardcoded plugin name in guest-components. Link 1 and Link 2.

We need the support in guest-components for additional plugin invocations in trustee.