Move IDS_PASSWORD_MANAGER_EMPTY_LOGIN to component resources
The string "(No username)" is currently used in the password manager bubble, but became useful also for password-field suggestions introduced by https://codereview.chromium.org/
773573004/.
This CL ensures, that when a user gets a suggestions pop-up in a password field, and has an empty username saved with a password, the suggestion explicitly mentions the username is missing, instead of displaying a blank suggestion. This is consistent with the bubble.
As a side-effect, the corresponding string is moved from chrome to components resources.
BUG=442191,410963
R=vasilii@chromium.org
Review URL: https://codereview.chromium.org/
785233009
Cr-Commit-Position: refs/heads/master@{#308635}