Use encrypted keychain for account management

[RMacfarlane]

export namespace authentication {
    export function getPassword(key: string): Thenable<string | null>;
    export function setPassword(key: string, value: string | null): Thenable<void>;
}

[Matelasse]

@RMacfarlane Will this address #98214 and remove the need of gnome-keyring for non-gnome linux distributions?

[Matelasse]

FWIW this new auth workflow is completely unusable on linux
This point hasn't been brought to light because the feature is still insiders, and I guess the core team testers don't use linux much, but I can tell you that once this lands in Stable you'll see many issues regarding this.