[SETUPLIB] Additions for filesup.c and inicache.c.

- In DoesFileExist(): Call NtOpenFile with FILE_GENERIC_READ instead of the more generic GENERIC_READ access right.
- OpenAndMapFile(): Add support for opening & mapping files with write access (to be used latter).

svn path=/branches/setup_improvements/; revision=74710

- Split IniCacheLoad() and IniCacheSave() into: themselves & IniCacheLoadByHandle() and IniCacheSaveByHandle(),
  respectively, so that we can load & save INI files if we already have an opened handle to them.

svn path=/branches/setup_improvements/; revision=74711

base/setup/lib/filesup.h

@@ -68,12 +68,13 @@ NtPathToDiskPartComponents(
 
 NTSTATUS
 OpenAndMapFile(
-    IN HANDLE RootDirectory OPTIONAL,
-    IN PCWSTR PathNameToFile,
+    IN  HANDLE RootDirectory OPTIONAL,
+    IN  PCWSTR PathNameToFile,
     OUT PHANDLE FileHandle,         // IN OUT PHANDLE OPTIONAL
     OUT PHANDLE SectionHandle,
     OUT PVOID* BaseAddress,
-    OUT PULONG FileSize OPTIONAL);
+    OUT PULONG FileSize OPTIONAL,
+    IN  BOOLEAN ReadWriteAccess);
 
 BOOLEAN
 UnMapFile(