Refactor datastore to its own package
This MR moves datastore to its own package. Having datastore in the praefect
package can lead to import cycles if for instance, we want to use datastore in the internal/praefect/services
package.
This MR is mostly changing references, but it also refactors a couple of tests that relied on reaching into datastore's unexported variables.
Edited by GitLab Release Tools Bot