Co-Authored-By: Court Ewing <[email protected]>

Co-Authored-By: Aleh Zasypkin <[email protected]>

1. Fleshed out motivation, this RFC doesn't prevent errors, but isolates the
   impact on the rest of Kibana.
2. Added a footnote explaining that sync lifecycles can still block on sync
   for loops, so it's not a perfect guarantee (from @azasypkin).
3. Updated IContextProvider type signature in (2) to match latest master
4. Dynamically reloading configuration changes should be limited to a
   whitelist, risky changes like the Elasticsearch host should still require a
   complete restart. Added to (3) based on
   elastic#45796 (comment)
5. Added Section 5, "Core should expose a status signal for Core services &
   plugins" (from @joshdover)
6. Added the drawback that incorrect, but valid config would not block Kibana,
   and might only be surfaced when the associted API/UI gets used (from
   @azasypkin)

Co-Authored-By: Josh Dover <[email protected]>

Co-Authored-By: Josh Dover <[email protected]>