Merge pull request #11190 from zaryabzip/feat/system-flexible-memory

feat(libkernel): implement sceKernelMapNamedSystemFlexibleMemory

docs/dev/debt/libkernel.md

@@ -133,6 +133,7 @@
 - [sceKernelPrintBacktraceWithModuleInfo](../../../core/libs/prx/libkernel/Unimplemented.cpp) (libkernel) - imported by PS4 titles, which do not load without it, and added without an implementation: declared without parameters, every call throws
 
 - [pthread_timedjoin_np](../../../core/libs/prx/libkernel/Pthread/Posix/Thread.cpp) (libkernel, NID `PkS44IGrDkM`) - the signature follows [ps5-payload-dev/sdk](https://github.com/ps5-payload-dev/sdk/blob/a7685ce8e97ce1f8a4f38253a41d54241c9124f1/include/freebsd/pthread_np.h#L71); deadline validation, absolute realtime deadlines, error precedence and join ownership follow [FreeBSD libthr](https://github.com/freebsd/freebsd-src/blob/d106002967eff712894ab8b5337bbbff106ce5e0/lib/libthr/thread/thr_join.c). The [public 3.20 export table](https://github.com/DNNDHH/PS5-3.20_Libs/blob/b2a77c09cd71c01f34c790cfbe98c751a13262ad/libkernel.c) lists this NID, but PS5 behavior and module/library versions have not been measured. Realtime is rechecked at most two seconds apart while waiting. After guest cleanup completes, final native thread teardown uses the existing unbounded join and may finish after the deadline; host teardown is not bounded by this implementation.
+- [sceKernelMapNamedSystemFlexibleMemory](../../../core/libs/prx/libkernel/DirectMemory/Export.cpp) (libkernel) - the PS5 system budget and the `sceKernelVirtualQuery` record of a system map are unmeasured. It is not charged to the game flexible budget, as in [shadPS4](https://github.com/shadps4-emu/shadPS4/blob/30f4170896ce974353a6f6486d0ecec179aec54b/src/core/libraries/kernel/memory.cpp#L354-L391), which charges only its flexible type; fpPS4 ignores `MAP_SYSTEM` and charges it. It reports as flexible, as in fpPS4; shadPS4 reports it as not flexible. Checks, alignment and placement are `sceKernelMapNamedFlexibleMemory`'s, so flag 0x8000 and protection 0x800 throw, unmeasured. A null name or one of 32 bytes or more throws, unmeasured: shadPS4 returns `EFAULT` or `ENAMETOOLONG` before mapping, [fpPS4](https://github.com/red-prig/fpPS4/blob/04cefd43e6fddd1ab033e7980cd356d14c964905/kernel/ps4_map_mm.pas#L1121-L1209) maps it unnamed. Closes when: measured on a PS5
 
 ### Functional