base: Refine Range_allocator::alloc_aligned

This patch changes the 'alloc_aligned' interface as follows:

- The former 'from' and 'to' arguments are replaced by a single
  'range' argument.

- The distinction of the use cases of regular allocations vs.
  address-constrained allocations is now overed by a dedicated
  overload instead of relying on a default argument.

- The 'align' argument has been changed from 'int' to 'unsigned'
  to be better compatible with 'addr_t' and 'size_t'.

Fixes #4067

repos/dde_bsd/src/lib/audio/pci.cc

@@ -76,7 +76,7 @@ class Pci_driver : public Bsd::Bus_driver
 			                   Pci_driver &drv)
 			: Genode::Allocator_avl(&alloc), env(env), _drv(drv) { }
 
-			Genode::addr_t alloc(Genode::size_t size, int align)
+			Genode::addr_t alloc(Genode::size_t size, unsigned align)
 			{
 				using namespace Genode;