BIGIP: Add support for lsnpool (CGNAT)

[PrashantSunkari]

Complete task list for CGNAT related work:

• LSNpool collection and resource + tests

• LSN log profile collection and resource + tests

• Add missing ALG profile - IPsecALG

• (Future: not part of this issue) ALG log profile collection and resource + tests

• (Future: not part of this issue) Add support for FWNAT (CGNAT equivalent from AFM)

First 3 tasks will allow following user stories:

1. User is able to create LSN pool without lsn log profile
2. User is able to create LSN pool with lsn log profile
3. User is able to create a virtual and attach a lsn pool and ALG profile

Future tasks will allow following user stories:

1. User is able to create ALG log profile and attach it to a ALG profile
2. User is able to create FWNAT source translation object
3. User is able to create FWNAT policy
4. User is able to create FWNAT log profile
5. User is able to create a virtual with FWNAT policy

[PrashantSunkari]

Please assign this to me. I am already close to submitting a pull request.