Consider enabling abandoning a flow directly for another flow

Consider an app with this arrangement.

> src/main/webapp/WEB-INF/faces-config.xml
> src/main/webapp/flowA/flowA-flow.xml
> src/main/webapp/flowA/flowA.xhtml
> src/main/webapp/flowB/flowB-flow.xml
> src/main/webapp/flowB/flowB.xhtml
> src/main/webapp/flowC/flowC-flow.xml
> src/main/webapp/flowC/flowC.xhtml
> src/main/webapp/index.xhtml
> src/main/webapp/site-template.xhtml

All .xhtml pages in this app are template clients of
site-template.xhtml. The site-template.xhtml has a row of buttons along
the top that allow immediate navigation to all of the flows. The intent
is that whatever flow you're in, you want to abandon it and enter the
new flow when the corresponding button is clicked. This is not a flow
call, but rather should be treated as an atomic "abandon/enter".

The current specification does not support this cleanly.
#### Affected Versions
[2.2]

Start with src/main/webapp/WEB-INF/faces-config.xml and the flowA-flow.xml, flowB-flow.xml, and flowC-flow.xml files to understand the current flow definitions. Review how the shared site-template.xhtml buttons navigate between flows. Done means the project has a specified and supported way to abandon the current flow and enter the selected flow atomically.

Written by the indexing model from the issue text.