Refactor link wizard configuration for field type 'Link'

[typecat]

Although the properties blindLinkFields and blindLinkOptions are self-explanatory for experienced TYPO3 integrators, it is strange if some properties are listing a deny list instead of an allow list (linke e.g. allowedExtensions does). Also, names are not self-explanatory for beginners. (See documentation)

This might confuse people new to TYPO3. Therefore we should refactor these two options to showLinkAttributes (default: all) instead of blindLinkFields, and allowLinkTypes (default: all) instead of blindLinkOptions.