Bug 23168: Enable plugins using plain SQL

Bug 23168: Enable plugins using plain SQL

To test:
- On a clean 18.11.x, install a plugin [1]
- Run:
  $ sudo koha-mysql kohadev
  > SELECT * FROM plugin_data;
=> SUCCESS: Notice there's a __INSTALLED_VERSION__ line for your plugin
- Checkout latest master, restart all the things
- Run:
  $ updatedatabase
=> FAIL: It fails on 18.12.00.069 because the plugin_methods table doesn't exist
- Run:
  $ sudo koha-mysql kohadev
  > SELECT * FROM plugin_data;
=> FAIL: No __ENABLED__ line for your plugin
- Apply the patch
- Run:
  $ updatedatabase
=> SUCCESS: Update passes the 18.12.00.069 step correctly
- Run:
  $ sudo koha-mysql kohadev
  > SELECT * FROM plugin_data;
=> SUCCESS: There's an __ENABLED__ line for your plugin
- Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>