[Feature request] Allow to pass side-data param to typeorm

Motivation: #68

TypeORM has an ability to pass data as an additional free-shape param to repository operations, that is available on the query runner instance.

// user sends request during entity save
postRepository.save(post, { data: { request: request } });

// in logger you can access it this way:
logQuery(query: string, parameters?: any[], queryRunner?: QueryRunner) {
    const requestUrl = queryRunner && queryRunner.data["request"] ? "(" + queryRunner.data["request"].url + ") " : "";
    console.log(requestUrl + "executing query: " + sql);
}

The example is from the end of: https://github.com/typeorm/typeorm/blob/master/docs/logging.md#using-custom-logger

If the passed data will be configurable somehow (maybe an async callback that gets request context of something more high-level/) it will be possible to implement #68 with

[kevinmelo]

Nothing yet? need to get current user from request on Subscriber…

[power-f-GOD]

How did you do that?