Generic.Strings.UnnecessaryHeredoc incorrectly converts tabs into spaces in heredoc #1320

Describe the bug

If --tab-width is set, the fixer for Generic.Strings.UnnecessaryHeredoc incorrectly converts tabs into spaces in lines edited in the heredoc.

Code sample

Note this file must be indented using tabs, not spaces.

<?php

$var = <<<EOF
	Normal line
	Test \$escaped var
	Normal line
EOF;

Custom ruleset

N/A

To reproduce

Steps to reproduce the behavior:

1. Create a file called test.php with the code sample above.
2. Run phpcbf -s --tab-width=8 --standard=Generic --sniffs=Generic.Strings.UnnecessaryHeredoc test.php
3. Examine the file.

Expected behavior

File content is

<?php

$var = <<<'EOF'
	Normal line
	Test $escaped var
	Normal line
EOF;

Actual behavior

File content is

<?php

$var = <<<'EOF'
	Normal line
        Test $escaped var
	Normal line
EOF;

i.e. the line "Test $escaped var" is indented with 8 spaces rather than one tab.

Versions (please complete the following information)

Additional context

Add any other context about the problem here.

Please confirm

• I have searched the issue list and am not opening a duplicate issue.
• I have read the Contribution Guidelines and this is not a support question.
• I confirm that this bug is a bug in PHP_CodeSniffer and not in one of the external standards.
• I have verified the issue still exists in the 4.x branch of PHP_CodeSniffer.