Add Attn config option for clearing Attn Interrupts

Added attn config option
Added UT for attn config object
Added UT for cli that uses attn config object

Signed-off-by: austinfcui <austinfcui@gmail.com>
Change-Id: I0e30ebf4d94de676814bf5e173691c4d1ee362cb
diff --git a/attn/attn_handler.cpp b/attn/attn_handler.cpp
index 59dfab3..3252078 100644
--- a/attn/attn_handler.cpp
+++ b/attn/attn_handler.cpp
@@ -78,8 +78,12 @@
  */
 void attnHandler(Config* i_config)
 {
-    // Clear attention interrupts that may still be active (MPIPL)
-    clearAttnInterrupts();
+    // Check if enClrAttnIntr is enabled
+    if (true == i_config->getFlag(enClrAttnIntr))
+    {
+        // Clear attention interrupts that may still be active (MPIPL)
+        clearAttnInterrupts();
+    }
 
     // Vector of active attentions to be handled
     std::vector<Attention> active_attentions;