Move the StyleCI config in the repository and enable strict types

.styleci.yml

@@ -0,0 +1,16 @@
+preset: recommended
+
+enabled:
+    - phpdoc_no_empty_return
+    - concat_with_spaces
+    - declare_strict_types
+
+disabled:
+    - phpdoc_to_comment
+    - unary_operators_spaces
+    - concat_without_spaces
+    - empty_return
+    - new_with_braces
+    - phpdoc_align
+    - phpdoc_separation
+    - align_double_arrow