Add option to include interface metadata

[marein]

This pull request brings the same functionality as

SerializerBuilder::create()
    ->includeInterfaceMetadata();

to the bundle configuration. I've only written a test for the happy path. If you're interested in this feature and want me to write more, please let me know.

I hope I didn't miss a pull request or issue where this topic was already discussed.

[marein]

Tests are failing because master is broken with php 7.2.

There was 1 warning:

1) JMS\SerializerBundle\Tests\Cache\CacheClearerTest::testClear
Cannot stub or mock class or interface "Psr\Cache\CacheItemPoolInterface" which does not exist

[goetas]

Nice! thanks!