Helper cleanup

[gsteel]

Q	A
BC Break	no
New Feature	yes
QA	yes

Description

• Gets psalm updated and deals with errors introduced by the upgrade, and by upstream types and deprecations.
• Drops PHP 7.3
• Stringifies all Zend related classes (For psalm)
• Laminas-view minimum 2.20
• Use the trait in upstream view to signal deprecation of inheritance in the shipped view helpers

The namespaced path stack resolver is a bit of a mess for psalm because various parameter and return types conflict with those that are inherited. Ideally, I think it just needs to not inherit from laminas-view and just do its own thing, but that'll need to go into a 3.0 right?

[Ocramius]

Something is off with the target branch 😬

[gsteel]

There's no 2.5.x branch yet. Can you make one please @Ocramius and I'll rebase 👍

[Ocramius]

Fogot to change the branch here - now done, and ready to release :)

[Ocramius]

Thanks @gsteel!