Add expression language support

[mpdude]

Currently, the params used in ObjectRoute definitions are property path expressions (https://symfony.com/doc/current/components/property_access.html).

For certain use cases, more flexibility would be helpful. For example, assume a blog post can be archived. When you link to such a blog post, you need to include the post's year in an extra URL parameter: ?year=....

Something like #[ObjectRoute(..., params: ['year' => 'year'])] does not work, since the property access component cannot evaluate conditional expressions.

This PR adds a new configuration parameter named paramExpressions and uses the Symfony ExpressionLanguage component to evaluate it.

Example: #[ObjectRoute(..., paramExpressions: ['year' => 'this.isArchived ? this.year : null'])]

Expressions given in paramExpressions can access two variables: this is the object on which the route is being generated, and params gives access to all parameter values. Those are the combination of the extraParams passed to the object router, and all params evaluated through property access expressions as previously.

In order to make optional parameters possible, the parameter name in paramExpressions can be prefixed with ? to indicate that a parameter should not be used (filtered out) when the expression evaluates to null. So, #[ObjectRoute(..., paramExpressions: ['?year' => 'this.isArchived ? this.year : null'])] would only pass the year parameter to the underlying router when the blog post has been archived.

Resolves #12.