Generic/LanguageConstructSpacing: exclude space from prepareForOutput()

This sniff uses `Common::prepareForOutput()` in two places to make
whitespace visible in error messages. Among other things, the method
replaces spaces with a UTF-8 middot character. The middot character
in the output can break tools that pipe PHPCS output through non-UTF-8
environments (see squizlabs/PHP_CodeSniffer 2652).

For the `IncorrectSingle` error, the spaces-only case now reports a
descriptive count like "found 2 spaces" instead of displaying
middot characters. For tabs or newlines, `prepareForOutput()` is kept
but with `[' ']` as the `$exclude` parameter, so that any spaces in the
content are displayed as-is.

For the `IncorrectYieldFrom` and `IncorrectYieldFromWithComment` errors,
the same `$exclude` parameter is passed, so that spaces between `yield`
and `from` are no longer replaced with middots.

Author: rodrigoprimo

src/Standards/Generic/Sniffs/WhiteSpace/LanguageConstructSpacingSniff.php

@@ -113,7 +113,7 @@ public function process(File $phpcsFile, int $stackPtr)
             }
 
             $error = 'Language constructs must be followed by a single space; expected 1 space between YIELD FROM found "%s"';
-            $data  = [Common::prepareForOutput($found)];
+            $data  = [Common::prepareForOutput($found, [' '])];
 
             if ($hasComment === true) {
                 $phpcsFile->addError($error, $stackPtr, 'IncorrectYieldFromWithComment', $data);
@@ -139,8 +139,16 @@ public function process(File $phpcsFile, int $stackPtr)
         if ($tokens[($stackPtr + 1)]['code'] === T_WHITESPACE) {
             $content = $tokens[($stackPtr + 1)]['content'];
             if ($content !== ' ') {
-                $error = 'Language constructs must be followed by a single space; expected 1 space but found "%s"';
-                $data  = [Common::prepareForOutput($content)];
+                if (trim($content, ' ') === '') {
+                    // Only space characters: report the count.
+                    $found = $tokens[($stackPtr + 1)]['length'] . ' spaces';
+                } else {
+                    // Contains tabs or newlines: make them visible.
+                    $found = '"' . Common::prepareForOutput($content, [' ']) . '"';
+                }
+
+                $error = 'Language constructs must be followed by a single space; expected 1 space but found %s';
+                $data  = [$found];
                 $fix   = $phpcsFile->addFixableError($error, $stackPtr, 'IncorrectSingle', $data);
                 if ($fix === true) {
                     $phpcsFile->fixer->replaceToken(($stackPtr + 1), ' ');