Specify $project array shape for UpdateFetcherInterface and UpdateManagerInterface

Problem/Motivation

Modules implementing UpdateFetcherInterface will trigger a phpstan warning "has parameter $project with no value type specified in iterable type array. "

Steps to reproduce

Run phpstan analyze at level 6 or higher, on a module implementing UpdateFetcherInterface.

Proposed resolution

Specify the array shape of $project in UpdateFetcherInterface. We can also specify the return shape of UpdateManagerInterface::getProjects() as it is defined as the reference array type.

Remaining tasks

User interface changes

None

API changes

No API change, this just adds a more specific type definition to the phpdoc based on existing documentation.

Data model changes

Release notes snippet