Requests are pushed onto the request stack twice, popped once

Problem/Motivation

• Symfony\Component\HttpKernel\HttpKernel::handleRaw() pushes $request onto the stack and Symfony\Component\HttpKernel\HttpKernel::finishRequest() pops it.
• DrupalKernel::preHandle() also pushes $request onto the stack, but there's no matching pop.
• As a result, at the conclusion of a subrequest, the stack still contains the subrequest. One consequence of this is that on a comment permalink page (e.g., /comment/1), drupalSettings.path.currentPath is 'node/1' instead of 'comment/1'. I don't know if there are other, more important, consequences.

Proposed resolution

Introduce RequestStackWrapper decorator for request_stack and pass it to http_kernel.basic instead of symfovy's one to be able to remove it in additional subscriber StackMiddlewareSubscriber runnig after KernelDestructionSubscriber

Sum-up in #2613044-85: Requests are pushed onto the request stack twice, popped once

Remaining tasks

Get RTBC and commit

User interface changes

no

API changes

2 new services for core: decorator of request stack and stack clean-up after kernel destroyed

Data model changes