Currently, profileManager filters profiles based on their creator/owner and the "current user"'s UID.
This causes DefaultUserProfileID(uid) to work incorrectly when the UID doesn't match the current user.
While we plan to remove the concept of the "current user" completely, we're not there yet.
In this PR, we fix DefaultUserProfileID by updating profileManager to allow checking profile access
for a given UID and modifying helper methods to accept UID as a parameter when returning
matching profiles.
Updates #14823
Signed-off-by: Nick Khyl <nickk@tailscale.com>