The error handler screens for oracle warnings from php oci8 driver
and converts them to a truncated query result exception. This also adds a test
that demonstrates the issue where a result set larger than the oci8
default prefetch value is queried, but a truncated
row set is returned due to the dataset being invalidated during the
fetch sequenece.

Fix truncated oracle fetch result

Deprecate Statement::execute in favor of Statement::executeStatement/executeQuery

[GH-4553] Simplify error handling in the OCI8 driver

Following methods are returning Doctrine\DBAL\Driver\Statement as before :
- Doctrine\DBAL\Connection::executeQuery()
- Doctrine\DBAL\Query\QueryBuilder::execute()

Fix BC break on QueryBuilder::execute()

Collect type coverage metrics, add badge to README

Attribute type coverage metric to 3.1.x instead of 2.13.x

…db0f4870b21.63151745

Merge release 2.13.1 into 3.0.x

[GH-4613] Use utf8mb4 instead of utf8 for testing connection charset