Extract the profiler to a new component

[jelte]

This pull request is a replacement for symfony#10374

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	yes
Tests pass?	yes
Fixed tickets	n/a
License	MIT
Doc PR	not use how to handle documentation

This pull request extracts the HTTP profiler from the HttpKernel component to a new dedicated component: Profiler.

The goals are to improve the general architecture and usability of the component as stated by @webmozart ( symfony#10374 (comment) )
as it stands now no BC is broken as the original DataCollectors are still supported by the new Profiler.

New DataCollectors and Profiler no longer require a Request and Response.
DataCollectors are should be able to collect data from other sources, which will prevent some ugly hacks that were previously required, they will still require to listen to events to collect the data, I don't see a way around this, but this doesn't seem a big issue.

If a DataCollector requires the Request, it should have the RequestStack and get it from there, the Responses can be added just like Controllers are added, by subscribing to the Kernel Events.

$httpProfiler = new HttpProfiler($requestStack, $storageInterface);
$httpProfiler->addCollector(new RequestDataCollector($requestStack));
$httpProfiler->addCollector(new ExceptionDataCollector());
$httpProfiler->addCollector(new FormDataCollector());

// Runtime data is collected
$profile = $httpProfiler->collect();

$requestData = $profile->get('request');

// Late data is collected
$httpProfiler->save($profile);

To debate:

• rename Profiler::collect() to Profiler::profile() or other name that makes slightly more sense. (+ would help on BC)
• provide ConsoleProfiler, will require some interface changes to the WebProfiler or a console version

Todo's:

• add additional tests especially for DataCollectors.
• submit changes to the documentation
• add significant readme
• gather feedback for my changes