Fix Xdebug disconnecting after php finished if multiple connections are allowed

Summary:

• If we launch a php xdebug process (browser) multiple connections are supported by default. If the debugged script finishes, the debug session do not keep

listening for additional connections.

• Various code fixes and some refactorization.

Test Plan:

• Launch a php script for debug (with some breakpoint defined).
• When script finishes, reload the url(on the browser), php debugger will accept the connection and start debugging the script

Reviewers: brauch, pprkut, mwolff

Reviewed By: mwolff

Subscribers: mwolff, pprkut, kdevelop-devel

Tags: KDevelop

Differential Revision: https://phabricator.kde.org/D18122