Support for generating HTML docs

[oleg-nenashev]

The idea is to utilize the ManPageGenerator, and then render the produced Asciidoc as HTML.
Not ready

[oleg-nenashev]

The current version passes unit tests, but actual invocations fail. Update to the recent JRuby version did not help

ig-yaml, faascinator, resteasy]
2021-07-04 08:16:52,122 ERROR [io.qua.ver.htt.run.QuarkusErrorHandler] (executor-thread-1) HTTP Request to /doc failed, error id: abbf5053-b900-4498-8cb3-29f29104b52f-1: org.jboss.resteasy.spi.UnhandledException: org.jruby.exceptions.LoadError: (LoadError) no such file to load -- asciidoctor
	at org.jboss.resteasy.core.ExceptionHandler.handleApplicationException(ExceptionHandler.java:106)
	at org.jboss.resteasy.core.ExceptionHandler.handleException(ExceptionHandler.java:372)
	at org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:218)
	at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:519)
	at org.jboss.resteasy.core.SynchronousDispatcher.lambda$invoke$4(SynchronousDispatcher.java:261)
	at org.jboss.resteasy.core.SynchronousDispatcher.lambda$preprocess$0(SynchronousDispatcher.java:161)
	at org.jboss.resteasy.core.interception.jaxrs.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:364)
	at org.jboss.resteasy.core.SynchronousDispatcher.preprocess(SynchronousDispatcher.java:164)
	at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:247)
	at io.quarkus.resteasy.runtime.standalone.RequestDispatcher.service(RequestDispatcher.java:73)
	at io.quarkus.resteasy.runtime.standalone.VertxRequestHandler.dispatch(VertxRequestHandler.java:138)
	at io.quarkus.resteasy.runtime.standalone.VertxRequestHandler.access$000(VertxRequestHandler.java:41)
	at io.quarkus.resteasy.runtime.standalone.VertxRequestHandler$1.run(VertxRequestHandler.java:93)
	at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2415)
	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1452)
	at org.jboss.threads.DelegatingRunnable.run(DelegatingRunnable.java:29)
	at org.jboss.threads.ThreadLocalResettingRunnable.run(ThreadLocalResettingRunnable.java:29)
	at java.base/java.lang.Thread.run(Thread.java:834)
	at org.jboss.threads.JBossThread.run(JBossThread.java:501)
Caused by: org.jruby.exceptions.LoadError: (LoadError) no such file to load -- asciidoctor
	at org.jruby.RubyKernel.require(org/jruby/RubyKernel.java:974)
	at RUBY.require(uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:83)
	at RUBY.<main>(<script>:12)

[oleg-nenashev]

Looks like the issue is similar to asciidoctor/asciidoctorj#647