Generic/UnconditionalIfStatement: handle FQN true/false/null

This sniff checks for `if`/`elseif` which only contain "true" or "false", i.e. don't actually compare to anything.

This commit fixes the sniff to still function correctly when it encounters "fully qualified true/false".

Includes tests.

Author: jrfnl

src/Standards/Generic/Sniffs/CodeAnalysis/UnconditionalIfStatementSniff.php

@@ -75,7 +75,7 @@ public function process(File $phpcsFile, $stackPtr)
         for (; $next <= $end; ++$next) {
             $code = $tokens[$next]['code'];
 
-            if (isset(Tokens::$emptyTokens[$code]) === true) {
+            if (isset(Tokens::$emptyTokens[$code]) === true || $code === T_NS_SEPARATOR) {
                 continue;
             } else if ($code !== T_TRUE && $code !== T_FALSE) {
                 $goodCondition = true;

src/Standards/Generic/Tests/CodeAnalysis/UnconditionalIfStatementUnitTest.1.inc

@@ -11,3 +11,8 @@ if (true) {
 if (file_exists(__FILE__) === true) {
 
 }
+
+// Check handling of case and FQN state.
+if (\true) {
+} else if (\FALSE) {
+}

src/Standards/Generic/Tests/CodeAnalysis/UnconditionalIfStatementUnitTest.php

@@ -50,9 +50,11 @@ public function getWarningList($testFile='')
         switch ($testFile) {
         case 'UnconditionalIfStatementUnitTest.1.inc':
             return [
-                3 => 1,
-                5 => 1,
-                7 => 1,
+                3  => 1,
+                5  => 1,
+                7  => 1,
+                16 => 1,
+                17 => 1,
             ];
 
         default: