Can be merged when database rows have been updated to
no longer use skin version.
* Drop migration code
* Drop skin version preference
* Drop default skin version and existing accounts skin version
* Move skin definitions into skin.json
* Repurpose SkinVector as an abstract class
* Update READMEs
Bug: T301930
Bug: T294995
Bug: T302627
Change-Id: I7454d8f1cfdef81e7f3df476d8ce86736b46fff2
Namespaceless class aliases are left behind for migration purposes.
They can be removed at a later date when dependant extensions
and skins are fully updated.
Bug: T301204
Change-Id: I2b37c1889ff862ec8bb41325fc9f654c673cd115
A new vector-2022 skin is added. This will be the eventual home
of the new Vector skin when we are ready to migrate.
Please see SkinVector class for the migration plan to simulate this
as part of testing.
Bug: T291098
Change-Id: Ibaddf94a5bfb5e21bbbaf1e0aa1b343a3f566d2d
