PHP 7.0 Support

Problem/Motivation

Currently our composer.json calls out PHP7.0 as supported.

I tend to align that in semver a projecting dropping PHP support should only be done in a major release. Even though 8.x-1.x is not technically semver I prefer to align it to the extent possible.

PHP8.4 for implicit nullable can only be fixed in PHP7.1 and above. These are not critical for PHP8.4 as they will not be required until PHP9 however they do create warnings when error_reporting is enabled. These warnings currently break PHPUnit tests although 🐛 beStrictAboutOutputDuringTests=true or failOnRisky=true causing test failures due to PHP8.4 Implicit Nullable deprecation Active may solve this, or we can add our own phpunit.xml.dist to fix.

Currently some commits have added changes that exist in PHP7.1 or newer breaking PHP7.0 in the code base.

Steps to reproduce

See attached

Proposed resolution

TBD

Remaining tasks

Decide on minimum supported PHP version
Implement fixes to restore compatibility if necessary or to adjust composer.json.
Implement Minimum PHP Verison Linting to enforce support for that version of PHP to prevent future accidental breaches.

User interface changes

None

API changes

TBD

Data model changes

None