cs fix

object type

conversionFailedUnserialization

type hinting & finally restore error handler

cs: use function

type hint

sort use alphabetically

code quality improvements

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.

Fixes https://github.com/doctrine/dbal/issues/3114

This should take care of most idiosyncracies.

See
https://stackoverflow.com/questions/1881853/select-without-a-from-clause-in-oracle

The Mysql family does not seem to like that one.