Correct URL for categories if Blog is on /home

[lerni]

Description

true in BlogObject->getLink() to get correct URL for categories also if Blog is on /home

If Blog is on /home, $this->Blog()->Link() returns just / but should return /home for categories. Adding true as parameter in https://github.com/silverstripe/silverstripe-blog/blob/4/src/Model/BlogObject.php#L86 to ->Link()fixes this. See also:
https://github.com/silverstripe/silverstripe-cms/blob/5/code/Model/SiteTree.php#L715

Manual testing steps

Install Blog on /home and see categories fail

[User Warning] Request handler SilverStripe\CMS\Controllers\ModelAsController does not have a url_segment defined. Relying on this link may be an application error
GET /category/...

Line 573 in /var/www/html/vendor/silverstripe/framework/src/Control/RequestHandler.php

Issues

• BlogObject filter URLs break if the Blog is the homepage #606

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