[PATCH phosphor-objmgr] Avoid introspection during discovery

[OpenBMC Patches]

Speed up discovery by calling GetManagedObjects on any ObjectManagers.
Fall back on introspection for parent elements or services that don't
implement one.

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/openbmc/phosphor-objmgr/11)
<!-- Reviewable:end -->


https://github.com/openbmc/phosphor-objmgr/pull/11

Brad Bishop (1):
  Avoid introspection during discovery

 phosphor-mapper | 90 ++++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 77 insertions(+), 13 deletions(-)

-- 
2.8.2