Provide two cases: one to install nginx httpg, one for nginx stable

Try to create two rpm, one for ngx with httpg patch, one for voms module

This script is used during the CI.

It is moved from .devocontainer to docker folder, probably this is not the correct place.

* Explicitly install build-time deps needed for this package
* Take the httpg patch from this repo

* Start from the upstream SPEC file.
* Use the %{name} macro instead of explicitly repeating openresty-voms
* Use system zlib, openssl and pcre dependencies and do not specify minimum
  versions
* Remove unused macros oroprefix, {zlib,pcre,openssl}_prefix
* The voms_module_prefix macro is assumed
* Mv-ing openresty binary in openresty-voms seems irrelevant
* Don't consider "tapset" files, they don't exist (any more)
* For debug builds use -Og
* Review the packaging script
  - Minimize the list of build-time packages to install
  - Set the voms_module_prefix macro in the .rpmmacros file. The prefix is
    on the command line, with a default
  - Build only the optimized RPM
* Start docker:dind with --tls=false to avoid timeouts during CI

Issue #17

This commit introduces the ngx-voms docker image, and modifies the CI
configuration to build the image.