refactor(build): python generate_test_list script

This change introduces generate_test_list.py which is exactly like
generate_test_list.pl except written in python. This helps remove a
dependency on perl as well as a dependency on perl's libxml bindings.
The only required dependency is python3 and its standard library.

Tested by generating tests_list.c/h for each xml file and each platform
and comparing it against the output from the original script.

Signed-off-by: Jim Ray <jimray@google.com>
Change-Id: If0fa8d0e45bf58ce35081aaeb7a9320dfcefdbf9
diff --git a/docs/getting_started/requirements.rst b/docs/getting_started/requirements.rst
index bea412e..f38964a 100644
--- a/docs/getting_started/requirements.rst
+++ b/docs/getting_started/requirements.rst
@@ -23,7 +23,9 @@
 
 ::
 
-    sudo apt-get install device-tree-compiler build-essential git perl libxml-libxml-perl
+    sudo apt-get install device-tree-compiler build-essential git python3
+
+Note that at least Python 3.7 is required.
 
 Download and install the GNU cross-toolchain from Arm. The TF-A Tests have
 been tested with version 12.2.Rel1 (gcc 12.2):