fbt: 'target' field for apps; lib debugging support (#1995)

* fbt: added 'target' field to application manifest
* fbt: earlier pagination setup for gdb
* fbt: added LIB_DEBUG flag
* fbt: sdk: added SDK_MAP_FILE_SUBST

scripts/fbt/util.py

@@ -1,7 +1,6 @@
 import SCons
 from SCons.Subst import quote_spaces
 from SCons.Errors import StopError
-from SCons.Node.FS import _my_normcase
 
 import re
 import os
@@ -58,3 +57,9 @@ def extract_abs_dir_path(node):
         raise StopError(f"Can't find absolute path for {node.name}")
 
     return abs_dir_node.abspath
+
+
+def path_as_posix(path):
+    if SCons.Platform.platform_default() == "win32":
+        return path.replace(os.path.sep, os.path.altsep)
+    return path