Create DB session provider(based on xorm) (#13031)

Create DB session provider(based on xorm) (#13031)

* Create Xorm session provider

This PR creates a Xorm session provider which creates
the appropriate Session table for macaron/session.

Fix #7137

Signed-off-by: Andrew Thornton <art27@cantab.net>
* extraneous l

Signed-off-by: Andrew Thornton <art27@cantab.net>
* fix lint

Signed-off-by: Andrew Thornton <art27@cantab.net>
* use key instead of ID to be compatible with go-macaron/session

Signed-off-by: Andrew Thornton <art27@cantab.net>
* And change the migration too.

Signed-off-by: Andrew Thornton <art27@cantab.net>
* Update spacing of imports

Co-authored-by: 6543 <6543@obermui.de>
* Update modules/session/xorm.go

Co-authored-by: techknowlogick <matti@mdranta.net>
* add xorm provider to the virtual provider

Signed-off-by: Andrew Thornton <art27@cantab.net>
* prep for master merge

* prep for merge master

* As per @lunny

* move migration out of the way

* Move to call this db session as per @lunny

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: techknowlogick <matti@mdranta.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>