#MIFOSX-1566 Added min/max number of clients per group rule for activate/activating group

###### Features
1> Only minimum number of clients rule can be set (no limitation on maximum number of clients)
2> Only maximum number of clients rule can be set (no limitation on minimum number of clients)
3> Both minimum number of clients rule and maximum number of clients rule can be set together
4> Above rules are validate only on active groups or during activation of clients.
5> While adding new client to a group maximum number of clients rule need to satisfy

###### Known issues
 But none of the above rule is validated during closing of client(belongs to a group) or transferring of the client from one group to another group or dis-associating of client from a group
The reason is for operational convenience, example, in case of client death, one has to close the client irrespective of groups total number of clients may fall below minimum number of clients rule.
Check list
- [ ]  Integration test cases written - can't be done as m_group_level does not have any write APIs
- [x]  Pull request has a Jira issue
- [x]  JIRA number as a part of the commit message
- [x]  Code has been formatted
- [x]  Work is present in a single commit
- [x]  Rebased on top of the latest code from develop branch
- [ ]  "gradlew licenseFormatMain licenseFormatTest licenseFormatIntegrationTest" has been run, No new file is added
- [ ]  API documentation, does not have any impact on API docs