libSceAppInstUtil technical debt

sceAppInstUtilAppIsInUpdating, sceAppInstUtilAppGetSize, sceAppInstUtilAppInstallPkg, sceAppInstUtilAppPrepareOverwritePkg, sceAppInstUtilAppRecoverApp, sceAppInstUtilAppUnInstallAddcont, sceAppInstUtilAppUnInstallPat, sceAppInstUtilAppUnInstallTheme, sceAppInstUtilAppUnInstallTypes, sceAppInstUtilGetInstallProgressInfo, sceAppInstUtilGetInstallProgress and sceAppInstUtilGetPrimaryAppSlot (libSceAppInstUtil) - names and NIDs are present in the PS5 3.20 export inventory, but no credible prototype was found. They are declared without parameters only to resolve the known imports; this is not an ABI claim and callers must not call them until a prototype is verified. The other seven declarations follow SharpProspero
sceAppInstUtilAppIsInInstalling (libSceAppInstUtil) - throws, as its prototype is disputed: SharpProspero's AppInstUtil.cs passes an int* that receives the answer, while its PackageInstaller.cs passes a NUL-terminated id and reads the return value, as the PS4 headers declare bool sceAppInstUtilAppIsInInstalling(const char* contentId) (flatz, OpenOrbis). Writing through the argument would overwrite a caller's id under the second form

sceAppInstUtilInitialize, sceAppInstUtilTerminate, sceAppInstUtilAppExists (libSceAppInstUtil) - sceAppInstUtilAppExists writes 1 only for the running title's id, as another title cannot be launched (sceSystemServiceLaunchApp throws). SharpProspero gives the meanings but no error codes, so calls outside an sceAppInstUtilInitialize/sceAppInstUtilTerminate pair, a second initialization and null pointers throw. The non-zero value a console writes for an installed title is unmeasured