Added yum query to Packages.yaml

Currently "old" versions of RHEL are not supported as they do not have dnf. I added yum support to resolve this issue

artifacts/definitions/Linux/RHEL/Packages.yaml

@@ -1,6 +1,6 @@
 name: Linux.RHEL.Packages
 description: |
-  Parse packages installed from dnf
+  Parse packages installed from dnf or yum
 
 parameters:
   - name: DNFGrokExpression
@@ -12,8 +12,14 @@ sources:
       SELECT OS From info() where OS = 'linux'
 
     query: |
-        SELECT * FROM foreach(row={
+        LET exec = SELECT * FROM foreach(row={
           SELECT grok(grok=DNFGrokExpression, data=Stdout) AS Parsed
-          FROM execve(argv=["dnf", "--quiet", "list", "installed"], sep="\n")
+          FROM execve(argv=cmd, sep="\n")
           WHERE count() > 2
         }, column="Parsed")
+        
+        SELECT * FROM switch(
+            a=exec(cmd=["dnf", "--quiet", "list", "installed"]),
+            b=exec(cmd=["yum", "--quiet", "list", "installed"]),
+            c={SELECT log(level="ERROR",message="Could not retrieve Package Information") FROM scope()}
+            )