Faster bugreports (1/n)

Adds a thread pool to dumpstate.

Bug: 136262402
Test: atest dumpstate_test
Change-Id: I83b48a696c60fafbd4cb0dd62d3acceaa43caabb
Merged-In: I83b48a696c60fafbd4cb0dd62d3acceaa43caabb
(cherry picked from commit 3432b93ad0e423a3bdd0b87fe3f3dabb9d572dae)
4 files changed