Add total IP count and available IP count in IPPool.Status

**User Story**

As a developer/user I would like to get the total IP count and available IP count of an IPPool CR by checking its status field.

**Detailed Description**

[A clear and concise description of what you want to happen.]

**Anything else you would like to add:**

[Miscellaneous information that will assist in solving the issue.]

/kind feature
