Add new tab in settings panel for WP Button Manager. about divi-paypal

@keyurptl I think we can improve upon this or at least clean it up a little bit. We have a few different scenarios that can happen here.

• I have PayPal for Divi installed as well as PayPal WP Button Manager, and they are both active.

  • This looks good, and it shows me that the plugin is already installed.

• I have PayPal for Divi installed as well as PayPal WP Button Manager, but only PayPal for Divi is active.

  • Right now I end up with the "Get it Now" button and a message under the plugin ad box that tells me the Button Manager is not installed/activated.

• I have PayPal for Divi installed but I don't have PayPal WP Button Manager installed at all.

  • This gives me the same exact output as the second scenario.

Here is what I'd like to see different...

• If the BM plugin is installed but not active, the "Get it Now" button should simply turn in to an "Activate" button, and this would allow you to actually activate the plugin from here the same way you could from the plugins page. Our message below in this case would say "Activate the PayPal WP Button Manager plugin if you would like to use it to manage PayPal buttons in WordPress."

• If the BM plugin is not installed at all, then the "Get it Now" button should say "Install Now" and it would be installed just like you're installing it through the Add New Plugin window in WordPress. In thise case our message below can say "Install the PayPal WP Button Manager plugin for a more advanced PayPal Button manager that is fully compatible with PayPal for Divi."