fix wrong email when use gitea as OAuth2 provider (#7640) (#7647)

when you use gitea as OAuth2 provider, the /api/v1/user should return
user primary email as identifier, which is unique in OAuth2 clients.

this patch use convert.ToUser replace all u.APIFormat in api requests,
return primary email when caller is yourself or admin.

routers/api/v1/admin/user.go

@@ -91,8 +91,7 @@ func CreateUser(ctx *context.APIContext, form api.CreateUserOption) {
 	if form.SendNotify && setting.MailService != nil {
 		models.SendRegisterNotifyMail(ctx.Context.Context, u)
 	}
-
-	ctx.JSON(201, u.APIFormat())
+	ctx.JSON(201, convert.ToUser(u, ctx.IsSigned, ctx.User.IsAdmin))
 }
 
 // EditUser api for modifying a user's information
@@ -181,7 +180,7 @@ func EditUser(ctx *context.APIContext, form api.EditUserOption) {
 	}
 	log.Trace("Account profile updated by admin (%s): %s", ctx.User.Name, u.Name)
 
-	ctx.JSON(200, u.APIFormat())
+	ctx.JSON(200, convert.ToUser(u, ctx.IsSigned, ctx.User.IsAdmin))
 }
 
 // DeleteUser api for deleting a user
@@ -326,7 +325,7 @@ func GetAllUsers(ctx *context.APIContext) {
 
 	results := make([]*api.User, len(users))
 	for i := range users {
-		results[i] = convert.ToUser(users[i], ctx.IsSigned, ctx.User != nil && ctx.User.IsAdmin)
+		results[i] = convert.ToUser(users[i], ctx.IsSigned, ctx.User.IsAdmin)
 	}
 
 	ctx.JSON(200, &results)