Forbidden deleting Real Service or Virtual Service if it bind any policy or Real Service Group

The Jira ticket is:

https://arraynetworks.atlassian.net/browse/TWSD-1308
The scenario is:

1. If a RS bind any Real Service Group, then it cannot be deleted

2. If a RS bind any Policy(Static Policy), then it cannot be deleted

3. If a RS doesn't bind any Real Service Group or Policy, it can be deleted

4. If a VS bind any Policy, then it cannot be deleted.

5. If a VS doesn't bind any Policy, then it can be deleted.
I have checked both CLI and WebUI,

you can see attachment for reference.
For WebUI changes,

the deletion API of RS is delete_rs_custom, it doesn't handle case if CLI return error message,

so I fix it.
For CLI changes,

I wrote some function in slb_rs_group_kern.c to check:

1. Is a RS bind any Static Policy(It is relationship between a VS and RS, so we should find VS to check the static policy member)

2. Is a VS bind any policy. I found there is structure with the information: slb_vs_t, so I use it and check it by different type of policy.

3. Is a RS bind any Real Service Group: We can get real_id by its name from slb_real_name_to_id, then check slb_mem for Real Service Group member.

Then I checked RS in no_slb_real_kern whether it is bind Real Service Group or Static Policy and show error message if so.

I also added new error code in proxy_errs.h

To use the function in slb_rs_group_kern.c, I added it to the header file: slb_kern.h,

Then check VS in the function no_slb_virtual_generic_kern of slb_vs_policy_kern.c file.

If the VS bind to any policy,

it will stop continue and show error message.