users: huge cleanup/dedupe, interface-based third-party services

shared "newUser" method is now "NewUserPostVerification", and is shared
between all routes which create a jellyfin account. The new
"NewUserFromInvite", "NewUserFromAdmin" and "NewUserFromConfirmationKey"
are smaller as a result. Discord, Telegram, and Matrix now implement the
"ContactMethodLinker" and "ContactMethodUser" interfaces, meaning code
is shared a lot between them in the NewUser methods, and the specifics
are now in their own files. Ombi/Jellyseerr similarly implement a
simpler interface "ThirdPartyService", which simply has ImportUser and
AddContactMethod routes. Note these new interface methods are only used
for user creation as of yet, but could likely be used in other places.

storage.go

@@ -509,6 +509,15 @@ func (st *Storage) GetDefaultProfile() Profile {
 	return defaultProfile
 }
 
+// MustGetProfileKey returns the profile at key k, or if missing, the default profile.
+func (st *Storage) MustGetProfileKey(k string) Profile {
+	p, ok := st.GetProfileKey(k)
+	if !ok {
+		p = st.GetDefaultProfile()
+	}
+	return p
+}
+
 // GetCustomContent returns a copy of the store.
 func (st *Storage) GetCustomContent() []CustomContent {
 	result := []CustomContent{}
@@ -584,12 +593,35 @@ func (st *Storage) DeleteActivityKey(k string) {
 	st.db.Delete(k, Activity{})
 }
 
-type TelegramUser struct {
-	JellyfinID string `badgerhold:"key"`
-	ChatID     int64  `badgerhold:"index"`
-	Username   string `badgerhold:"index"`
-	Lang       string
-	Contact    bool // Whether to contact through telegram or not
+type ThirdPartyService interface {
+	// ok implies user imported, err can be any issue that occurs during
+	ImportUser(jellyfinID string, req newUserDTO, profile Profile) (err error, ok bool)
+	AddContactMethods(jellyfinID string, req newUserDTO, discord *DiscordUser, telegram *TelegramUser) (err error)
+	Enabled(app *appContext, profile *Profile) bool
+	Name() string
+}
+
+type ContactMethodLinker interface {
+	PIN(req newUserDTO) string
+	Name() string
+	Required() bool
+	UniqueRequired() bool
+	UserVerified(PIN string) (ContactMethodUser, bool)
+	PostVerificationTasks(PIN string, u ContactMethodUser) error
+	DeleteVerifiedToken(PIN string)
+	Exists(ContactMethodUser) bool
+}
+
+type ContactMethodUser interface {
+	SetMethodID(id any)
+	MethodID() any
+	Name() string
+	SetJellyfin(id string)
+	Jellyfin() string
+	SetAllowContactFromDTO(req newUserDTO)
+	SetAllowContact(contact bool)
+	AllowContact() bool
+	Store(st *Storage)
 }
 
 type DiscordUser struct {
@@ -602,6 +634,24 @@ type DiscordUser struct {
 	JellyfinID    string `json:"-" badgerhold:"key"`
 }
 
+type TelegramUser struct {
+	TelegramVerifiedToken
+	JellyfinID string `badgerhold:"key"`
+	ChatID     int64  `badgerhold:"index"`
+	Username   string `badgerhold:"index"`
+	Lang       string
+	Contact    bool // Whether to contact through telegram or not
+}
+
+type MatrixUser struct {
+	RoomID     string
+	Encrypted  bool
+	UserID     string
+	Lang       string
+	Contact    bool
+	JellyfinID string `badgerhold:"key"`
+}
+
 type EmailAddress struct {
 	Addr                string `badgerhold:"index"`
 	Label               string // User Label.
@@ -686,6 +736,16 @@ type Invite struct {
 	UseReferralExpiry  bool                       `json:"use_referral_expiry"`
 }
 
+func (invite Invite) Source() (ActivitySource, string) {
+	sourceType := ActivityAnon
+	source := ""
+	if invite.ReferrerJellyfinID != "" {
+		sourceType = ActivityUser
+		source = invite.ReferrerJellyfinID
+	}
+	return sourceType, source
+}
+
 type Captcha struct {
 	Answer    string
 	Image     []byte // image/png