Introduce phpstan

[szepeviktor]

@TylerBarnes Is this PR okay?
Should I send it to your repo?

[szepeviktor]

Please see individual commits.

[szepeviktor]

@TylerBarnes ID should be a string as it goes into base64_encode
See https://github.com/ivome/graphql-relay-php/blob/master/src/Relay.php#L188

[TylerBarnes]

Thanks for this @szepeviktor !
I'll defer to @jasonbahl on this as he's much better on the PHP side than I am.
One thing I will note is that I intentionally removed composer packages before because it was bloating the plugin size and some people couldn't install the zip. This is more about our release process (there isn't one currently :p ). We'll be giving this plugin an overhaul soon and possibly moving it to it's own repo so we can put it on packagist. When we do that we'll be able to set up a better release process that keeps the final zip size smaller.

[szepeviktor]

All right.
👀 PHPStan keeps several eyes on your code with a little time investment: writing only testable code.
Please consider raising Level to max.

[szepeviktor]

@jasonbahl Friendly ping 🏓

[jasonbahl]

Hey, I don't maintain this plugin anymore.

I think it makes a lot of sense to add phpstan though! Use it on all my plugins now

[szepeviktor]

@TylerBarnes What do you suggest?