Add LONGTEXT as type in database!#403

Currently I cannot add fields with more than 255 characters, as per VARCHAR 255

Therefore wpDataTable cannot be used for a lot of different data types.

LONGTEXT | 4,294,967,295 (232−1) bytes = 4 GiB

https://dev.mysql.com/doc/refman/8.0/en/storage-requirements.html#data-types-storage-reqs-strings