[b4p] Introduce JS APIs for batch deletions of passwords/blacklists

This CL introduces removeSavedPasswords and removePasswordExceptions
APIs to chrome.passwordsPrivate, which allow deleting batches of
passwords/blacklists that are entirely restored upon call to
undoRemoveSavedPasswordOrException.

This is achieved by plumbing the APIs introduced in crrev.com/c/2193695.
In order to minimize unnecessary function duplication, all the C++
intermediary APIs now take batches as arguments. Only JS still exposes
APIs for individual deletion.

In future CLs, the JS APIs will be used to allow simultaneously deleting
versions of a same password stored in different PasswordStore's.

Bug: 1049141
Change-Id: I5852b1c4375caef4ac3e167ccd0fa9c30eeef9e0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2199148
Commit-Queue: Victor Vianna <victorvianna@google.com>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Friedrich [CET] <fhorschig@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#770034}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: a8cf33128752cd3aab474b684bd3d0d4f4bbc019
1 file changed