+ fixes issues in MysqlPlatform::getListTableIndexesSQL() and getListTableColumnsSQL() on MySQL 8.0

revert back MariaDb1027Platform

Closes #3187.

1. Use the actual dsdriver distribution
2. Introduced `AbstractPlatform::getCharMaxLength()` since `CHAR` and `VARCHAR` limitations are different on DB2.

If a PRIMARY KEY field is defined in sqlite without autoincrement then
keys might be reused when rows are deleted, explicitly settings autoincrement
will prevent this.

Autoincrement is not enabled by default due to additional overhead introduced
with autoincrement bookkeeping and should only be enabled when the additional
uniqueness is required.

For testing purposes and not only, it may be needed to evaluate an arbitrary SQL expression (see https://github.com/doctrine/dbal/pull/3013, https://github.com/doctrine/dbal/pull/3108). Instead of doing `str_replace()` on an expected string, one could specify the expression explicitly.

The SQLite and Oracle platforms produces a `ROUND()`'ed or `TRUNC()`'ated difference between the datetimes. However it should be the difference between dates.

A string is made of characters, an array might contain anything.

array_merge will not work with any iterable