timeout: rework timeout framework

* get rid of alarm abstraction
* get rid of Timeout::Time type
* get rid of pointer arguments
* get rid of _discard_timeout indirection
* get rid of 65th bit in stored time values
* get rid of Timeout_scheduler interface
* get rid of uninitialized deadlines
* get rid of default arguments
* get rid of Timeout::_periodic
* get rid of Timeout::Raw
* use list abstraction
* only one interface for timeout handlers
* rework locking scheme to be smp safe
* move all method definitions to CC file
* name mutexes more accurate
* fix when & how to set time-source timeout
* fix deadlocks

Fixes #3884

repos/base/src/timer/gpt/time_source.cc

@@ -17,8 +17,8 @@
 using namespace Genode;
 
 
-void Timer::Time_source::schedule_timeout(Genode::Microseconds  duration,
-                                          Timeout_handler      &handler)
+void Timer::Time_source::set_timeout(Genode::Microseconds  duration,
+                                     Timeout_handler      &handler)
 {
 	_handler = &handler;