Fixed incorrect handling of single quotes in SQL-Strings escaped by repeated single-quote (DBAL-1205)

According to the comment

// deleting duplicated foreign keys present on both on the orphanedForeignKey
// and the removedForeignKeys from changedTables

A check must be had on the $removedForeignKey so it does point on the removed table. Currently it does unset all keys removal even the one pointing on other table.

On the MySQLPlatform::getDropForeignKeySQL table name will not be escaped if the name is passed instead of the object table itself.

Since the getLocalTableName use the localTable property the object is always available, there is no reason not to use it.

The schema's name in the alter session command must not be quoted
https://docs.oracle.com/cd/B28359_01/server.111/b28310/general009.htm

fixes #1352

also refactors URL path evaluation into smaller methods

fixes #1106

When creating sqlite connections from a url with DriverManager, pass the 'path' key the driver expects instead of the 'dbname' key other drivers expect.

Backport #2273 to 2.5

fix usage of PDO::PGSQL_ATTR_DISABLE_PREPARES for pdo_pgsql extension setups not built from PHP core

fixes #2249

fixes #1339
closes #921

#2260 - loosening doctrine/common requirement: allowing 2.6.x

* fix tests to use new CTE-based method