Status report table PHP extensions row does not include zip extension when enabled

[izmeez]

Description of the need

On the Status report the row PHP extensions does not show zip extension when enabled.

Proposed solution

The zip extension must be enabled if the project installer module is enabled in which case it should show on this row and if it is missing when the installer module is enabled it should show as an error or warning at the top of the Status report.

Alternatives that have been considered

No alternatives have been considered.

Additional information

This was identified in an issue #6953 (comment)

Draft of feature description for Press Release (1 paragraph at most)

Backdrop now includes...

[izmeez]

The required PHP extensions are identified in core/modules/system/system.install file. However, the zip extension is only required when the project installer is enabled.

[izmeez]

This may be a duplicate of #3978

[avpaderno]

#3978 is about sites for which the extension is reported missing when it is instead installed. This issue is not a duplicate of that.