[OptionsResolver] Added a light-weight, low-level API for basic option resolving
[Security] add an AbstractVoter implementation
feature #11183 [Security] add an AbstractVoter implementation (Inoryy)

This PR was squashed before being merged into the 2.6-dev branch (closes #11183).

Discussion
----------

[Security] add an AbstractVoter implementation

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT
| Doc PR        | https://github.com/symfony/symfony-docs/pull/4257

The idea is to reduce boilerplate required to create custom Voter, doing most of the work for the developer and guiding him on the path by providing simple requirements via abstract methods that will be called by the AbstractVoter.

P.S. This is meant to be a [DX Initiative](https://github.com/symfony/symfony/issues?labels=DX&state=open) improvement.

Commits
-------

d3bafc6 [Security] add an AbstractVoter implementation
[Security] Added a REMOTE_USER based listener to security firewalls
feature #10698 [Security] Added a REMOTE_USER based listener to security firewalls (Maxime Douailin)

This PR was squashed before being merged into the 2.6-dev branch (closes #10698).

Discussion
----------

[Security] Added a REMOTE_USER based listener to security firewalls

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | /
| License       | MIT
| Doc PR        | symfony/symfony-docs#3912
TODO
- [x] submit changes to the documentation

I've seen myself implementing a few times a REMOTE_USER based authentication listener, as a large part of security modules for Apache (Kerberos, CAS, and more) are providing the username via an environment variable.

So I thought this could benefit the whole community if directly included in the framework. It is very similar to the X509AuthenticationListener, and basing the RemoteUserAuthenticationListener on the AbstractPreAuthenticatedListener is relevant and very convenient.

Using the X509AuthenticationListener could be possible, but it is confusing to use it directly when your authentication is not certificate based.

Please let me know if I need to update anything.

Regards

Commits
-------

a2872f2 [Security] Added a REMOTE_USER based listener to security firewalls
[Form] Changed "allow_html5" to "html5"
minor #11994 [Form] Changed "allow_html5" to "html5" (webmozart)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[Form] Changed "allow_html5" to "html5"

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

This is a follow-up to #8291, which I missed before it was merged. IMO "allow_html5" is a confusing name. We don't "allow" HTML5, but we use it - or we don't. I think "html5" conveys that meaning well and is shorter at the same time.

Commits
-------

ad171be [Form] Changed "allow_html5" to "html5"
feature #11716 [OptionsResolver] Added a light-weight, low-level API for basic option resolving (webmozart)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[OptionsResolver] Added a light-weight, low-level API for basic option resolving

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11705
| License       | MIT
| Doc PR        | symfony/symfony-docs#4159

See [the updated documentation](https://github.com/webmozart/symfony-docs/blob/issue11705/components/options_resolver.rst) for details on the usage of the simple API.

The most important motivation for this change is DX and speed. The basic features of the component should be easily usable in a wide variety of use cases without impacting performance.

For DX reasons, I added the static methods to the `Options` class, which makes the code concise and easy to read and understand:

```php
use Symfony\Component\OptionsResolver\Options;

$options = Options::validateRequired($options, 'format');

$options = Options::validateTypes($options, array(
    'format' => array('string', 'int'),
    'calendar' => 'int',
));

$options = Options::validateValues($options, array(
    'calendar' => array(
        \IntlDateFormatter::GREGORIAN,
        \IntlDateFormatter::TRADITIONAL,
    ),
));

$options = Options::resolve($options, array(
    'format' => null,
    'calendar' => \IntlDateFormatter::GREGORIAN,
));
```

If you need to distribute the option configuration, this PR also extracts the configuration part of the `OptionsResolver` class into a new class `OptionsConfig`, which can be passed around. When the configuration is complete, pass the config object to `Options::resolve()` as second argument:

```php
$config = new OptionsConfig();

$config->setDefaults(array(
    'format' => \IntlDateFormatter::MEDIUM,
    'calendar' => \IntlDateFormatter::GREGORIAN,
));

$options = Options::resolve($options, $config);
```

Consequently - since `OptionsResolver` extends `OptionsConfig` - the two following statements now become identical:

```php
$options = $resolver->resolve($options);
$options = Options::resolve($options, $resolver);
```

Commits
-------

9066025 [OptionsResolver] Added a light-weight, low-level API for basic option resolving
Previous PR
BC Concurrent Sessions Control