[Console] application/command as text/xml/whatever decoupling
merged branch jfsimon/console-descriptor (PR #7454)

This PR was squashed before being merged into the master branch (closes #7454).

Discussion
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[Console] application/command as text/xml/whatever decoupling

This PR removes description generation from `Command`, `Application` and `InputDefinition` classes and delegate it to specialized descriptor classes, making it dead simple to add new output formats.

**Maybe this could include other commands, like `router:debug` or `container:debug` (see #5740)?**

- [x] Add a `DescriptorProvider` which uses `DescriptorInterface` objects to describe things.
- [x] Add `txt` descriptors.
- [x] Add `xml` descriptors.
- [x] Add `json` descriptors.
- [x] Add `md` descriptors.
- [x] Remove obsolete methods.
- [x] Repair tests.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #6339

Commits
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51512e6 [Console] application/command as text/xml/whatever decoupling
[Process] Use new ProcessUtils::escapeArgument to escape ProcessBuilder prefix
[Process] Do not throw LogicException in ProcessBuilder::getProcess if no arguments are set but a prefix is
Currency translation
[Validator] updated Hungarian translation

updated and extended Hungarian translation
merged branch ikerib/basque-trans (PR #7822)

This PR was merged into the master branch.

Discussion
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[Validator] Added Basque translations of currency

Commits
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d50f488 Currency translation
merged branch kepten/master (PR #7823)

This PR was merged into the master branch.

Discussion
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[Validator] updated Hungarian translation

updated and extended Hungarian translation

Commits
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cf36126 [Validator] updated Hungarian translation
[Filesystem] Made sure Filesystem::dumpFile() overwrites an existing file.
merged branch romainneutron/process-builder (PR #7821)

This PR was merged into the master branch.

Discussion
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[Process] Fix two process-builder minor bugs

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

Everything is in the commit messages :

 - Use new ProcessUtils::escapeArgument to escape ProcessBuillder prefix
 - Do not throw LogicException in ProcessBuilder::getProcess if no arguments are set but a prefix is

Commits
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1de29b9 [Process] Do not throw LogicException in ProcessBuilder::getProcess if no arguments are set but a prefix is
209799b [Process] Use new ProcessUtils::escapeArgument to escape ProcessBuilder prefix
merged branch jakzal/filesystem-dump-file (PR #7820)

This PR was merged into the master branch.

Discussion
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[Filesystem] Made sure Filesystem::dumpFile() overwrites an existing file

#7753 introduced a change in behaviour. Before, ConfigCache simply used the ``rename()`` function to save a file. It was replaced by ``Filesystem::dumpFile()`` which internally uses ``Filesystem::rename()``. The later checks if file already exists and throws an exception if it exists.

This PR makes sure that ``Filesystem::dumpFile()`` removes the file before creating a new one.

Alternatively, we could introduce a third parameter to the ``Filesystem::rename()`` which would allow to overwrite the target file.

Before #7752:
* [CompilerDebugDumpPass](https://github.com/symfony/symfony/blob/d100ffaf761b46acdb2440c04602378b87b0d610/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/CompilerDebugDumpPass.php#L23) uses ConfigCache
* [ConfigCache](https://github.com/symfony/symfony/blob/d100ffaf761b46acdb2440c04602378b87b0d610/src/Symfony/Component/Config/ConfigCache.php#L103) uses the [rename()](http://uk1.php.net/rename) function (which overwrites a file if it exists)

After #7752:
* [CompilerDebugDumpPass](https://github.com/symfony/symfony/blob/ad47bc47380188041b7889f40e380ad3766a0110/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/CompilerDebugDumpPass.php#L23) uses the ``Filesystem::dumpFile()``
* [Filesystem::dumpFile()](https://github.com/webfactory/symfony/blob/ad47bc47380188041b7889f40e380ad3766a0110/src/Symfony/Component/Filesystem/Filesystem.php#L458) uses the [Filesystem::rename()](https://github.com/webfactory/symfony/blob/ad47bc47380188041b7889f40e380ad3766a0110/src/Symfony/Component/Filesystem/Filesystem.php#L239) (which throws an exception if file exists)

| Q | 	A
| ------------- | ---
| Bug fix?	| yes
| New feature?	| no
| BC breaks?	| no
| Deprecations?	| no
| Tests pass?	| yes
| Fixed tickets	| #7816
| License | 	MIT
| Doc PR	| ~

Commits
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4f4ec76 [Filesystem] Made sure Filesystem::dumpFile() overwrites an existing file.