Deprecate "service" connection parameter

[morozov]

Q	A
Type	bug/improvement

Even though the current behavior is explicitly documented, it looks nonsensical to me. If I specify the servicename parameter in connection configuration but don't add service = true, instead of being interpreted as SERVICE_NAME, servicename will be interpreted as SID:

echo EasyConnectString::fromConnectionParameters([
    'host' => 'localhost',
    'port' => 1521,
    'servicename' => 'BILLING',
]);

// (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521))(CONNECT_DATA=(SID=BILLING)))

Technically, the addition of || isset($params['servicename']) might be considered a BC break (servicename which was previously interpreted as SID will be interpreted as SERVICE_NAME), but I'd consider it a bug fix. If the user expects that the connection will use SID, they can use dbname.

In the short future, I want to deprecate the usage of dbname for Oracle connections in favor of introducing an explicit sid parameter. The "database" term is too vague in the context of Oracle.