Add APM Server to interactive upgrade guide

[debadair]

Add APM Server to the list of selectable stack components and show it in the list of steps if it is selected.

[simitt]

@debadair it would be great to have this in for the next release? How can we help with this?

[bmorelli25]

Deb - I'm hearing mixed reports: Is the upgrade guide going away? Or are there plans to update it?