Add request headers to web application output

Previously the web applications (grails, play, web) did not output the
request headers attached to each request.  This change causes those
values to be included.  In addition, this change refactored the
existing application to render the output data in the idiomatic way
for each application type.

[#53161743]
Merge 53161743-request-headers to master

[Completes #53161743]