Refactor ResteasyReactiveOutputStream so that it can be used by Quarkus CXF

[ppalaga]

Description

ResteasyReactiveOutputStream was written so that RESTeasy is able to run on top of Vert.x.
CXF works like RESTeasy: it also writes to a (Servlet)OutputStream and to make CXF able to run on top of Vert.x one needs a similar class. For some time, we had an adjusted static copy of ResteasyReactiveOutputStream in Quarkus CXF. At some point, we got issues related to chunking reported, that were fixed in Quarkus long time ago.
After that, I implemented a script that adapts ResteasyReactiveOutputStream.java at Quarkus CXF runtime which is a bit safer, but still rather fragile.

Implementation ideas

Hence, it would be nice if ResteasyReactiveOutputStream could be refactored in the following way:

• Make it independent of RESTeasy
• Possibly move it (along with its ancillary classes) to a separate module in Quarkus that depends only on vertx-web but does not depend on RESTeasy
• Or perhaps move the reafctored classes to Vert.x

@cescoffier encouraged me to prepare a PR which is underway.