shell: add option to disable pcspkr blacklisting

Unfortunately, there is a popular hoster that offers systems where blacklisting pcspkr results in a failure. Since these are virtual systems its not really relevant anyway. The simplest solution was to make it configurable.

Open to other solutions.

shell/defaults/main.yml

@@ -8,3 +8,5 @@ shell_software:
   - pwgen
   - snmp
   - telnet
+
+shell_blacklist_pcspkr: true