[Validator] Convert objects to string in comparison validators. Reapplies 6cf5e0812e6f20d60acbc0324abf96475e89b6ef
Allow basic auth in url. Improve regex. Add tests.
bug #11559 [Validator] Convert objects to string in comparison validators (webmozart)

This PR was merged into the 2.3 branch.

Discussion
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[Validator] Convert objects to string in comparison validators

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

In the [latest merge from 2.3 into 2.4](/symfony/symfony/commit/3bed1b7988e94a897a64c6a2ad3bf70bde9005c1), the changes from 6cf5e0812e6f20d60acbc0324abf96475e89b6ef in 2.4 got lost. This PR brings back these changes and backports them to 2.3.

The change is BC, because the former value `true` of the `$prettyDateTime` will be cast to `1`, which corresponds to the `PRETTY_DATE` format constant.

Commits
-------

273671e [Validator] Convert objects to string in comparison validators. Reapplies 6cf5e0812e6f20d60acbc0324abf96475e89b6ef
[Validator] Backported constraint validator tests from 2.5
Merge branch '2.3' into 2.4

* 2.3:
  [Validator] Backported constraint validator tests from 2.5
  Fix toolbar vertical alignment.
  [HttpFoundation] MongoDbSessionHandler supports auto expiry via configurable expiry_field
  [FrameworkBundle] add missing attribute to XSD
  Allow basic auth in url. Improve regex. Add tests.
  fix typos and syntax in Profiler controller method comments
  remove volatile tests
  [Console] fixed style creation when providing an unknown tag option
  [Validator] Convert objects to string in comparison validators. Reapplies 6cf5e0812e6f20d60acbc0324abf96475e89b6ef
  [HttpFoundation] Update QUERY_STRING when overrideGlobals

Conflicts:
	src/Symfony/Bridge/Doctrine/Tests/Validator/Constraints/UniqueValidatorTest.php
	src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
	src/Symfony/Component/Validator/Constraints/AllValidator.php
	src/Symfony/Component/Validator/Constraints/CollectionValidator.php
	src/Symfony/Component/Validator/Tests/Constraints/AbstractComparisonValidatorTestCase.php
	src/Symfony/Component/Validator/Tests/Constraints/CallbackValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/EqualToValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/FileValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/GreaterThanValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/IdenticalToValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/ImageValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/LessThanOrEqualValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/LessThanValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/NotEqualToValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/NotIdenticalToValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/UrlValidatorTest.php