[AMQ-7514] Replace non-inclusive terms in classic docs

[lucastetreault]

This change replaces references to master/slave with active/passive in the ActiveMQ "Classic" specific pages to the extent possible today. There are three main strategies for helping users through the change:

1/ An announcement about the changes.

2/ An info box on every page that was changed referring back to the announcement.

3/ Redirects for pages whose urls were renamed e.g: https://activemq.apache.org/masterslave to https://activemq.apache.org/activepassive