Enforce function declaration format in bash8

Check that function calls look like ^function foo {$ in bash8, and fix
all existing failures of that check.  Add a note to HACKING.rst

Change-Id: Ic19eecb39e0b20273d1bcd551a42fe400d54e938
diff --git a/lib/neutron_plugins/openvswitch b/lib/neutron_plugins/openvswitch
index f99eb38..bdbc5a9 100644
--- a/lib/neutron_plugins/openvswitch
+++ b/lib/neutron_plugins/openvswitch
@@ -7,14 +7,14 @@
 
 source $TOP_DIR/lib/neutron_plugins/openvswitch_agent
 
-function neutron_plugin_configure_common() {
+function neutron_plugin_configure_common {
     Q_PLUGIN_CONF_PATH=etc/neutron/plugins/openvswitch
     Q_PLUGIN_CONF_FILENAME=ovs_neutron_plugin.ini
     Q_DB_NAME="ovs_neutron"
     Q_PLUGIN_CLASS="neutron.plugins.openvswitch.ovs_neutron_plugin.OVSNeutronPluginV2"
 }
 
-function neutron_plugin_configure_service() {
+function neutron_plugin_configure_service {
     if [[ "$ENABLE_TENANT_TUNNELS" = "True" ]]; then
         iniset /$Q_PLUGIN_CONF_FILE ovs tenant_network_type gre
         iniset /$Q_PLUGIN_CONF_FILE ovs tunnel_id_ranges $TENANT_TUNNEL_RANGES
@@ -52,7 +52,7 @@
     done
 }
 
-function has_neutron_plugin_security_group() {
+function has_neutron_plugin_security_group {
     return 0
 }