Profile picker availability on startup

Specifies whether the profile picker is enabled, disabled or forced at the browser startup. By default the profile picker is not shown if the browser starts in guest or incognito mode, a profile directory and/or urls are specified by command line, an app is explicitly requested to open, the browser was launched by a native notification, there is only one profile available or the policy ForceBrowserSignin is set to true. If 'Enabled' (0) is selected or the policy is left unset, the profile picker will be shown at startup by default, but users will be able to enable/disable it. If 'Disabled' (1) is selected, the profile picker will never be shown, and users will not be able to change the setting. If 'Forced' (2) is selected, the profile picker cannot be suppressed by the user. The profile picker will be shown even if there is only one profile available.