Old records have a null value of file_store column.
This causes the problems with current direct_upload implementation,
as this makes it to choose Store::REMOTE instead of Store::LOCAL.

This change moves the store save when change saving the object.

Introduce `direct_upload` option for `uploads` which is gonna set a default storage to Object Storage and use Unicorn to save data

File uploads on objects storage should use hashed storage

Closes #4952

See merge request gitlab-org/gitlab-ee!4597

Fix migrate! method (Minimal fix with ExclusiveLock to prevent race conditions)

Closes #4928 and #4980

See merge request gitlab-org/gitlab-ee!4624

This reverts commit 54a575f1, reversing
changes made to c63af942.

EE: Trace as artifacts (FileStorage and ObjectStorage)

Closes #4171

See merge request gitlab-org/gitlab-ee!4258

Move uploads to object storage

Closes #4163

See merge request gitlab-org/gitlab-ee!3867

Transfer job archives after creation

See merge request gitlab-org/gitlab-ee!3646

Multiple artifacts ee

See merge request gitlab-org/gitlab-ee!3276

ObjectStoreUploader#migrate! uses with_callbacks to trigger verify_license!

Closes #3370

See merge request !2863

Can migrate LFS objects to S3 style object storage

Closes #2841

See merge request !2760

Object store for artifacts

Closes gitlab-ce#29203

See merge request !1762

it will also automatically prune empty directories for
`FileUploader`-based uploaders.