libpldmresponder: Migrate to pldm_entity_association_pdr_add_check()

pldm_entity_assocation_pdr_add() is deprecated in libpldm as it used
assert() for handling error cases.
pldm_entity_association_pdr_add_check() instead returns a value
indicating success or failure.

We throw a std::runtime_error for now which at least unwinds the stack,
unlike assert(). With this approach the problem is reduced to needing to
refactor internal pldmd APIs, rather than despairing at libpldm aborting
the process out of existence.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I08ebafc94cd7a392ec8f18b6c5feb75ba72cd028