[NTP][Enterprise] Add handler for Microsoft Auth Untrusted page

This adds a handler connection to the NTP's Microsoft Auth untrusted UI
to be used for sending access tokens (and later error messages) on to a
profile keyed service that will be created in a follow up CL.

For more context: the goal is to send the results of the authentication
call to a profile keyed service, which any NTP instances can observe and
update their UIs from. By storing the key in the service, module
handlers can also directly pull the access token to put directly into
headers for API calls to Microsoft.

Low-Coverage-Reason: HARD_TO_TEST Catching the call to CreatePageHandler will be flaky for the moment. It will be easier to catch when conditional rendering for the modules is in so it can be caught by watching for render changes. As it is, CreatePageHandler isn't called until the Microsoft Authentication Library is finished initializing, which doesn't have a visual to wait for.
Bug: 377380012
Change-Id: I56371342933120dc2f0c1be7827e84c02074feb3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6170348
Reviewed-by: Matthew Denton <mpdenton@chromium.org>
Commit-Queue: Riley Tatum <rtatum@google.com>
Reviewed-by: Paul Adedeji <pauladedeji@google.com>
Cr-Commit-Position: refs/heads/main@{#1407041}