Squiz/ForLoopDeclaration: improve the semicolon spacing determination

The `SpacingBeforeFirst/Second`/`SpacingAfterFirst/Second` checks did not handle situations where the spacing found was a new line.

The determination of `$spaces` has now been brought in line with other sniffs and will report `newline` when a new line was found.

Includes using the predetermined `length` of the token instead of doing length calculations.

For the "spaces before" situation, only a minor tweak has been made to the error message to acknowledge that more than just a space may have been found.

**Note**: This _does_ change the behaviour of the sniff for multi-line `for` declarations.
Previously a new line character would be regarded as "one space" and left alone.
Now, the new line (and other extraneous whitespace) will be removed.

Note: spacing _within_ expressions is not affected by this change.

Author: jrfnl

src/Standards/Squiz/Sniffs/ControlStructures/ForLoopDeclarationSniff.php

@@ -200,7 +200,7 @@ public function process(File $phpcsFile, $stackPtr)
             $prevNonWhiteSpace = $phpcsFile->findPrevious(T_WHITESPACE, ($semicolon - 1), $openingBracket, true);
             if ($semicolonCount !== 1 || $prevNonWhiteSpace !== $openingBracket) {
                 if ($tokens[($semicolon - 1)]['code'] === T_WHITESPACE) {
-                    $error     = 'Space found before %s semicolon of FOR loop';
+                    $error     = 'Whitespace found before %s semicolon of FOR loop';
                     $errorCode = 'SpacingBefore'.$humanReadableCode;
                     $fix       = $phpcsFile->addFixableError($error, $semicolon, $errorCode, $data);
                     if ($fix === true) {
@@ -225,7 +225,11 @@ public function process(File $phpcsFile, $stackPtr)
                 } else if ($tokens[($semicolon + 1)]['code'] === T_WHITESPACE
                     && $tokens[$nextNonWhiteSpace]['code'] !== T_SEMICOLON
                 ) {
-                    $spaces = strlen($tokens[($semicolon + 1)]['content']);
+                    $spaces = $tokens[($semicolon + 1)]['length'];
+                    if ($tokens[$semicolon]['line'] !== $tokens[$nextNonWhiteSpace]['line']) {
+                        $spaces = 'newline';
+                    }
+
                     if ($spaces !== 1) {
                         $error     = 'Expected 1 space after %s semicolon of FOR loop; %s found';
                         $errorCode = 'SpacingAfter'.$humanReadableCode;