Automatically enable the module that is providing the current database driver

Problem/Motivation

The module that is providing the current database driver cannot override backend services, plugins and EntityStorage classes during installation.

Proposed resolution

Automatically install/enable the module that is providing the current database driver during install process. Doing so right before or after the installation of the "system" module. In that way the module that is providing the current database can override everything it needs to (during the install process) in all other modules.

Remaining tasks

Review
Commit

User interface changes

None

API changes

Two new methods are added to the class Drupal\Core\Database\Connection: getProvider() and enableModuleProvidingDatabaseDriver(). The method getProvider() takes no parameters and returns the name of the module that is providing the database driver or "core" when there is no such module. The method enableModuleProvidingDatabaseDriver() also takes no parameters and enables the module that is providing the database driver. If there is no such module or that module is already enabled then the method does nothing.

Data model changes

None

Release notes snippet

TBD