Selfoss: Update to version 2.19

[mreid-tt]

Description

This PR contains the following:

1. Update Selfoss to version 2.19
2. Use SQLite database for faster performance

Fixes #
Closes #3786
Closes #3510
Closes #2210
Closes #2052

Checklist

• Build rule all-supported completed successfully
• New installation of package completed successfully
• Package upgrade completed successfully (Manually install the package again)
• Package functionality was tested
• Any needed documentation is updated/created

Type of change

• Package update

[mreid-tt]

@hgy59 following our initial discussion in #3786, this PR was created to modernise the Selfoss package. Do have a review and let me know what you think. I did note that even though this is a webservice type package and based on the example in demowebservice/Makefile, a SERVICE_USER is not required, it did not create the privilege config file. The build log for DSM 6 showed:

  ===>  NOT creating /github/workspace/spk/selfoss/work-dsm6/conf/privilege
  ===>  (privilege) DSM <= 6 and SERVICE_USER undefined

I suspect this is because I am not using a share worker for this package (unlike with ownCloud) as a share is not needed. Once I added the SERVICE_USER to the makefile in cb74418, the build for DSM 6 then showed:

  ===>  Creating /github/workspace/spk/selfoss/work-dsm6/conf/privilege
  ===>  (privilege) spksrc.service.privilege-installasroot

[mreid-tt]

@hgy59, on further examination of this, I realised that the PHP FPM modifications that I made previously under ownCloud would conflict with this package on DSM 6. As such, I have reworked the web interface setup on DSM 6 to remove this as part of a bug fix for ownCloud #5920.

For this PR, I have removed the similar code to modify the PHP FPM and have reverted the addition of the SERVICE_USER to the Makefile as it is not required.

EDIT: I've since re-added the SERVICE_USER because I was getting these errors in the install log:

chown: missing operand after '/volume1/@appstore/selfoss/tmp'
Try 'chown --help' for more information.