Check for use of deprecated API with Psalm

[alcaeus]

Follow-up to #8689.

This enables checks for usage of deprecated API in the psalm configuration and also updates the baseline to not report any errors. Deprecations will be fixed gradually.

[ostrolucky]

DeprecatedMethod was just an example I gave. There are a lot more deprecated* issue handlers in Psalm https://github.com/vimeo/psalm/blob/master/docs/running_psalm/error_levels.md:

DeprecatedClass
DeprecatedConstant
DeprecatedFunction
DeprecatedInterface
DeprecatedMethod
DeprecatedProperty
DeprecatedTrait

Maybe would be easier to bump psalm to level 3?

[alcaeus]

We'd have to bump to level 2, as the Deprecated* class of issues are treated as errors only from level 2 and lower. I'm ok with updating the baseline and require new code to be stricter, but then would definitely defer this change until 2.10. WDYT?

[alcaeus]

As a follow-up, here's the output when moving to level 2:

No errors found!
------------------------------
5995 other issues found.

And just for shits and giggles, here's what happens when we include tests:

No errors found!
------------------------------
18562 other issues found.

[ostrolucky]

Ok. What about other Deprecated* issue handlers? Do you want to include them in this PR, or you think DeprecatedMethod will do?

[alcaeus]

I'd add all others, but as you said: it might be easier to go to level 2. This puts more restrictions on new codes with existing issues being safely ignored through the baseline.

[greg0ire]

here's what happens when we include tests:

About that, @beberlei proposed to have some kind of sample calling code instead. That's looks a lot like what Marco did on the DBAL recently: doctrine/dbal#4638

[alcaeus]

Then let's not add tests. I've pushed a change to check level 2.

[greg0ire]

Looks good! Is there a Psalm command that allows to only see the deprecations?

[greg0ire]

Thanks @alcaeus !