[Password Manager] Switch password manager code to use "base/feature_list.h".
Changes so far:
A. 'enable-automatic-password-saving' feature.
B. 'enable-password-force-saving' feature.
C. 'enable-password-change-support' feature.
BUG=
561322
Committed:
https://crrev.com/906f9aee610d3f45e1cb98ed3f5aef9fb424b873
Cr-Commit-Position: refs/heads/master@{#363525}