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/nova_plugins/hypervisor-baremetal b/lib/nova_plugins/hypervisor-baremetal
index 660c977..2da1097 100644
--- a/lib/nova_plugins/hypervisor-baremetal
+++ b/lib/nova_plugins/hypervisor-baremetal
@@ -33,13 +33,13 @@
 # ------------
 
 # clean_nova_hypervisor - Clean up an installation
-function cleanup_nova_hypervisor() {
+function cleanup_nova_hypervisor {
     # This function intentionally left blank
     :
 }
 
 # configure_nova_hypervisor - Set config files, create data dirs, etc
-function configure_nova_hypervisor() {
+function configure_nova_hypervisor {
     configure_baremetal_nova_dirs
 
     iniset $NOVA_CONF baremetal sql_connection `database_connection_url nova_bm`
@@ -67,19 +67,19 @@
 }
 
 # install_nova_hypervisor() - Install external components
-function install_nova_hypervisor() {
+function install_nova_hypervisor {
     # This function intentionally left blank
     :
 }
 
 # start_nova_hypervisor - Start any required external services
-function start_nova_hypervisor() {
+function start_nova_hypervisor {
     # This function intentionally left blank
     :
 }
 
 # stop_nova_hypervisor - Stop any external services
-function stop_nova_hypervisor() {
+function stop_nova_hypervisor {
     # This function intentionally left blank
     :
 }