Fix UniqueConstraintViolationException while insert into oc_filecache

[MorrisJobke]

• fixes Doctrine\DBAL\Exception\UniqueConstraintViolationException: An exception occurred while executing 'INSERT INTO "oc_filecache"  #6160 by not being prone to the race condition in insertIfNotExists
• fixes Exception: Doctrine\\DBAL\\Exception\\DriverException | cannot start web service #12228 by not using a query that can result in a deadlock
• replaces the insertIfNotExists call with an insert which is wrapped into a try-catch block
• followup to Catch UniqueConstraintViolationException inside insertIfNotExist #12371

I would back port this one to stable13 and stable14 as well because it is a smaller and not that invasive version of #12371 and it also fixes the deadlocks.

[MorrisJobke]

It also said, that there is an sql injection problem (this came from our plugin to Phan). I double checked and the column as well as the argument are both properly escaped.

[kesselb]

INSERT INTO `oc_filecache` (`mimepart`,
                            `mimetype`,
                            `mtime`,
                            `size`,
                            `etag`,
                            `storage_mtime`,
                            `permissions`,
                            `parent`,
                            `checksum`,
                            `path_hash`,
                            `path`,
                            `name`,
                            `storage`)
VALUES ('11',
        '14',
        1542033752,
        544134,
        'b81868bb19bc3b3769e1954d2e387359',
        1542033752,
        27,
        2,
        '',
        '9a341df1023c4809dddef853beb3d4ee',
        'files/dummy-1440x960-Stones.jpg',
        'dummy-1440x960-Stones.jpg',
        1);

Query looks good and unique constraint is working. mimepart and mimetype passed as string and stored as bigint but insertIfNotExist works similiar 👍

[MorrisJobke]

Query looks good and unique constraint is working. mimepart and mimetype passed as string and stored as bigint but insertIfNotExist works similiar 👍

Yep - I didn't changed anything there. We can tackle the types later, but for now I want to go for the least intrusive way.