Support for Mysql 8 on Ubuntu 19.10

[bschmalhofer]

Ubuntu 19.10 ships with MySQL 8.0.20. MySQL 8.0 is the successor of MySQL 5.7. Looks like they dropped the 5 in order to confuse people. There are some changes in MySQL 8.0 that are relevant for OTOBO. See also https://dev.mysql.com/doc/refman/8.0/en/mysql-nutshell.html.

The individual topics will be handled in dependent issues:

• MySQL 8: user creation #4: Creating users with GRANT no longer works. The default authentication plugin has changed from 'mysql_native_password' to 'caching_sha2_password'
• MySQL 8: 'groups' is no longer allowed as unquoted table name #6: "groups" is now a reserved word and can no longer be used as an unquoted table name
• MySQL 8: don't set query_cache_size #9: The query cache has been removed. Especially the variable query_cache_size which is mentioned in the installation instructions
• The default character_set_server has changed from latin1 to utf8mb4. No action required here as the encoding utf8 is explicitly stated in the CREATE TABLE statements
• The character set utf8mb3, which is aliased by utf8, is now deprecated, no action required for this issue. Switching to utf8mb4 is not in the scope of this issue

[bschmalhofer]

OTOBO on MySQL 8 seems to work. Closing the issue.