hw: unify page-table mechanisms, remove exceptions thereby

[skalk]

After introducing a somehow generic page-table template tool for the Large-Physical-Addressspace-Extensions (LPAE) for ARMv7, this utility got widely copied over and adapted, e.g. for x86 and riscv. Unfortunately, instead of identifying the common mechanisms a bunch of slightly similar copies are now spread along the Genode codebase (potentially other copies exist for IOMMU, and GPU page-tables).
Moreover, all these copies took over exceptions from the page-table allocator API, and in the case of insertion, or lookup failure.
Aim of this issue is: to get rid of the exceptions (see issue #5245) on the one hand, and to simplify this kind of maintainance work for the future, by extracting generic utilities from the different page-table implementations, thereby reducing identical code pathes.