[HttpFoundation] MongoDbSessionHandler supports auto expiry and auto index creation

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11508
| License       | MIT
| Doc PR        | no

ToDo

 * [x] Fix Tests

Looking for feedback on this early PR.


This adds a config option that disables the PHP GC method call from doing anything,
It also means that the write method sets up the auto expiring index.


Ref: #11508
> It can be a documented edit and I'll remove from this code, at least the developer is in control I guess?

I'd suggest leaving it in a comment (as I did for the ZF class) or in the documentation (if this ever gets an entry).

Anecdotally, index creation for ODM is left to console commands, as we consider it part of the schema creation process. The best practice is definitely to leave index creation as part of the deployment process. There are some references in that Stack Overflow thread to doing it when the application starts, but that's likely for Java and the like, where the application and app server are one and the same.