Use pathlib more in doctor
Use pathlib more in doctor

Change-Id: I787c1c5aa878f205d2845718b60c2d471de667a4

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed