Add notification on new instance follower (server side)

server/controllers/api/users/my-notifications.ts

...alizers/migrations/0360-notification-instance-follower.ts

server/lib/activitypub/actor.ts

server/lib/activitypub/process/process-follow.ts

server/lib/emailer.ts

server/lib/job-queue/handlers/activitypub-follow.ts

server/lib/notifier.ts

server/lib/user.ts

server/middlewares/validators/user-notifications.ts

server/models/account/user-notification-setting.ts

server/models/account/user-notification.ts

server/tests/api/check-params/user-notifications.ts

server/tests/api/index-1.ts

server/tests/api/notifications/index.ts

server/tests/api/notifications/user-notifications.ts

server/tests/api/users/index.ts

shared/models/users/user-notification-setting.model.ts

shared/models/users/user-notification.model.ts

shared/utils/users/user-notifications.ts