Allow autoscale group and name override (#8324)

Updates AutoScaleManager/AutoScaleManagerImpl so that getNextVmHostName and checkAutoScaleVmGroupName can be overridden in derivative implementations to allow for custom naming conditions and restrictions. If possible, would like to include this in 4.19 since it is a trivial change.
This can be used to create an extension of AutoScaleManagerImpl.java, overriding these 2 methods

Author: Rene Glover

server/src/main/java/com/cloud/network/as/AutoScaleManager.java

@@ -55,4 +55,8 @@ public interface AutoScaleManager extends AutoScaleService {
     void checkIfVmActionAllowed(Long vmId);
 
     void removeVmFromVmGroup(Long vmId);
+
+    String getNextVmHostName(AutoScaleVmGroupVO asGroup);
+
+    void checkAutoScaleVmGroupName(String groupName);
 }

server/src/main/java/com/cloud/network/as/AutoScaleManagerImpl.java

@@ -1938,15 +1938,17 @@ public void updateVmDetails(Map<String, String> deployParams, Map<String, String
         }
     }
 
-    private String getNextVmHostName(AutoScaleVmGroupVO asGroup) {
+    @Override
+    public String getNextVmHostName(AutoScaleVmGroupVO asGroup) {
         String vmHostNameSuffix = "-" + asGroup.getNextVmSeq() + "-" +
                 RandomStringUtils.random(VM_HOSTNAME_RANDOM_SUFFIX_LENGTH, 0, 0, true, false, (char[])null, new SecureRandom()).toLowerCase();
         // Truncate vm group name because max length of vm name is 63
         int subStringLength = Math.min(asGroup.getName().length(), 63 - VM_HOSTNAME_PREFIX.length() - vmHostNameSuffix.length());
         return VM_HOSTNAME_PREFIX + asGroup.getName().substring(0, subStringLength) + vmHostNameSuffix;
     }
 
-    private void checkAutoScaleVmGroupName(String groupName) {
+    @Override
+    public void checkAutoScaleVmGroupName(String groupName) {
         String errorMessage = "";
         if (groupName == null || groupName.length() > 255 || groupName.length() < 1) {
             errorMessage = "AutoScale Vm Group name must be between 1 and 255 characters long";