FIx follow requests

Closes #1357

See merge request pleroma/pleroma!1918

Fix `SetNotNullForUsers` migration

See merge request pleroma/pleroma!1913

Move following relationships to a separate table

Closes #1233

See merge request pleroma/pleroma!1814

User info migration improvements

See merge request pleroma/pleroma!1887

Add NOT NULL constraints for users table

See merge request pleroma/pleroma!1910

Add NOT NULL constraints for user_invite_tokens table

See merge request pleroma/pleroma!1909

Add NOT NULL constraints for thread_mutes table

See merge request pleroma/pleroma!1908

Add NOT NULL constraints for scheduled_activities table

See merge request pleroma/pleroma!1907

Add NOT NULL constraints for registrations table

See merge request pleroma/pleroma!1906

Add NOT NULL constraints for push_subscriptions table

See merge request pleroma/pleroma!1905

Add NOT NULL constraints for password_reset_tokens table

See merge request pleroma/pleroma!1904

Add NOT NULL constraints for objects table

See merge request pleroma/pleroma!1903

Add NOT NULL constraints for oauth_authorizations table

See merge request pleroma/pleroma!1902

Add NOT NULL constraints for oauth_tokens table

See merge request pleroma/pleroma!1901

Add NOT NULL constraints for notifications table

See merge request pleroma/pleroma!1900

Add NOT NULL constraints for moderation_log table

See merge request pleroma/pleroma!1899

Add NOT NULL constraints for markers table

See merge request pleroma/pleroma!1898

Add NOT NULL constraints for lists table

See merge request pleroma/pleroma!1897

Add NOT NULL constraints for instances table

See merge request pleroma/pleroma!1896

Add NOT NULL constraints for filters table

See merge request pleroma/pleroma!1895

Add NOT NULL constraints for conversation_participations table

See merge request pleroma/pleroma!1894

Merge branch 'refactor/db-not-null-constraints-for-conversation_participation_recipient_ships' into 'develop'

Add NOT NULL constraints for conversation_participation_recipient_ships table

See merge request pleroma/pleroma!1893

Add NOT NULL constraints for config table

See merge request pleroma/pleroma!1892

Add NOT NULL constraints for bookmarks table

See merge request pleroma/pleroma!1891

Add NOT NULL constraints for apps table

See merge request pleroma/pleroma!1890

Add NOT NULL constraints for activity_expirations table

See merge request pleroma/pleroma!1889

Add NOT NULL constraints for activities table

See merge request pleroma/pleroma!1888

Clarify that postgres contrib modules are required, not just postgres.

See merge request pleroma/pleroma!1911