Container parameters in Route#condition

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Adds ability to use parameters in route conditions like you can use them in container definitions:

```php
contact:
    path:     /contact
    defaults: { _controller: AcmeDemoBundle:Main:contact }
    condition: "request.headers.get('User-Agent') matches '%allowed_user_agents%'"
```

As you could see replacement of the placeholder happens before ExpressionLanguage will tokenize and compile the expression so it looks kinda ad-hoc and primitive.

This PR is a different implementation of #12869 which is I think is too overcomplicated for this feature.
Hm, what will happen if someone really relies on a condition containing a plain `%foo%` string where `foo` also is a container parameter (this might not be very likely, but can be true, right?)?