introduce PHPStan (retry)

[sasezaki]

Q	A
Documentation	no
Bugfix	no
BC Break	no
New Feature	no
RFC	no
QA	yes

Description

• At this PR set up target level as 5, because level 6 is a lot of "no value type specified" occurred. and I feel requires remove current deprecations before level up to 6 or over.
• travis setup is borrowed from phpstan fixes zendframework/zend-servicemanager#272

[samsonasik]

@sasezaki please rebase against latest develop branch

[sasezaki]

I give up rebase includes zendframework/zend-servicemanager#272, and would to Reopening of setup.
(Adding baseline & modify it, to be clear change reason )

[sasezaki]

according this vote,
https://github.com/laminas/technical-steering-committee/blob/main/meetings/minutes/2020-08-03-TSC-Minutes.md#vote-on-static-analysis-tooling
I close this PR .

[Ocramius]

@sasezaki I think the fixes are valid: just need to swap out the CI tool

[sasezaki]

This is a mistake for

    /**
     * {@inheritDoc}
     *
     * @return DispatchableInterface
     */
    public function __invoke(ContainerInterface $container, $requestedName, array $options = null)

Not returned DispatchableInterface, just returned object - requestedName instance