[Chore] Introduce psalm (#962)

* chore: introduce psalm

* chore: remove dead code

* chore: run psalm workflow

* chore: run psalm in grumphp

* normalize composer.json

* chore: analyse --> analyze

* chore: just remove psalm when running tests instead of worrying about dependency mismatch hell

Co-authored-by: mr-feek <[email protected]>

psalm.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0"?>
+<psalm
+    errorLevel="7"
+    resolveFromConfigFile="true"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+    errorBaseline="psalm-baseline.xml"
+>
+    <projectFiles>
+        <directory name="src" />
+        <ignoreFiles>
+            <directory name="vendor" />
+        </ignoreFiles>
+    </projectFiles>
+</psalm>