[HttpFoundation] Added ParameterBag::getBoolean

Added the getBoolean method as a convenience on top of the pre-existing
ParameterBag::filter method
feature #11086 [HttpFoundation] Added ParameterBag::getBoolean (peterjmit)

This PR was merged into the 2.3-dev branch.

Discussion
----------

[HttpFoundation] Added ParameterBag::getBoolean

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

At the moment to pull a boolean value from a request the user has to use `ParameterBag::filter` or use `filter_var` directly

```php
// GET /products?hide_archived=true
$request->query->filter('hide_archived', false, false, FILTER_VALIDATE_BOOLEAN);
// or
filter_var($request->query->get('hide_archived'), FILTER_VALIDATE_BOOLEAN);
```

This is a pure convenience addition, adding a nice way of pulling a boolean value from a query string or request body (especially if http form/url encoded).

Example usage:
```php
// GET /products?hide_archived=true
$request->query->getBoolean('hide_archived'); // (boolean) true
$request->query->get('hide_archived'); // (string) "true"

// GET /products?hide_archived=1
$request->query->getBoolean('hide_archived'); // (boolean) true

// GET /products?hide_archived=false
$request->query->getBoolean('hide_archived'); // (boolean) false

// GET /products?hide_archived=banana
$request->query->getBoolean('hide_archived'); // (boolean) false
```

Commits
-------

36c58f8 [HttpFoundation] Added ParameterBag::getBoolean