VarSetType rename to SetVarType, add phan/phpstan/phpunit tests

Breaking change:
VarSetType/VarSetTypeNull classes have been renamed to
SetVarType/SetVarTypeNull

Added phan/phpstan static checkes and settings
Add phpunit tests (in test/phpunit) that are an exact copy from the
trunk folder unit tests

The phan/phpstan tests have been updated to work with the composer layout

config files with static defines needed for certain classes are stored
in test/configs (config.php, config.other.php, config.master.php)

src/Convert/Extends/SetVarTypeMain.php

@@ -9,7 +9,7 @@ declare(strict_types=1);
 
 namespace CoreLibs\Convert\Extends;
 
-class VarSetTypeMain
+class SetVarTypeMain
 {
 	/**
 	 * If input variable is string then returns it, else returns default set