Fix $XAPP_DESCRIPTOR_PATH parser bug

While xapp-frame-cpp assumes that $XAPP_DESCRIPTOR_PATH is a filename, the
xapp-onboarder sets it up as a directory. This assumption causes xapps
based on xapp-frame-cpp to crash on startup even using default helm charts.

This change fixes this bug and adds some logic to determine if the
$XAPP_DESCRIPTOR_PATH is a directory or a filename.
This change also adds test cases for $XAPP_DESCRIPTOR_PATH parser.

Issue-ID: RIC-883

Signed-off-by: Alexandre Huff <alexandrehuff@utfpr.edu.br>
Change-Id: I1d29c8c8ae80028accc5d3e29ea571b6365121ac
diff --git a/CHANGES b/CHANGES
index 5cc1d83..5d6ee6e 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5,6 +5,10 @@
 # has several changes.  Multiple blank lines between versions are
 # squished to one.
 
+2022 05 February; version 2.3.6
+	Fixed bug on XAPP_DESCRIPTOR_PATH parser.
+	Add test cases for XAPP_DESCRIPTOR_PATH parser.
+
 release = E
 2021 03 December; version 2.3.5
 	Taking in new RMR version 4.8.0. Also one bug fix added.