Add redirects for TER
- typo3.org/fileadmin/ter/* -> extensions.typo3.org/fileadmin/ter/*
- typo3.org/extensions/repository/view/[extkey] -> extensions.typo3.org/extension/[extkey]
- typo3.org/extensions/repository -> extensions.typo3.org
- typo3.org/extensions/repository/download/[extkey]/[versionNumber]/[fileFormat] -> extensions.typo3.org/extension/download/[extkey]/[versionNumber]/[fileFormat]