[res] Dump resources timings in dumpsys

ResourceTimer collects the timings for resource getters, and
we should dump those in the same bugreport section as the
resources history, as it's just a few lines that would add
quite a bit of insight on how device was performing

+ a bit of improvements in the dumping function

Bug: 319137634
Test: manual 'dumpsys resources'
Flag: EXEMPT bugfix
Change-Id: I5fa70d3326038a236c655d762447a9ab13dee8ae