Add support for generating Dockerfile.c9s

[phracek]

This pull request adds support for generation Dockefile.c9s files. And specify distgen configuration file.

Signed-off-by: Petr "Stone" Hracek phracek@redhat.com

[phracek]

The configuration file for C9S already exist here: https://github.com/devexp-db/distgen/blob/main/distgen/distconf/centos-stream-9-x86_64.yaml

[pkubatrh]

LGTM

[phracek]

[test]

[phracek]

[test]

[phracek]

let's try one more time [test]

[phracek]

Fedora test failed here:  ```bash

08:36:11 out: [PASSED] for 'hw' test_run_hw_application 08:36:11 out: [PASSED] for 'hw' test_incremental_build 08:36:11 out: [PASSED] for 'hw' test_build_express_webapp 08:36:11 out: [PASSED] for 'clients' express 08:36:11 out: [FAILED] for 'clients' pino 08:36:11 out: [PASSED] for 'clients' prom-client 08:36:11 out: [PASSED] for 'binary' test_run_binary_application

[phracek]

CentOS 7 test failed here:

1m[INFO] Testing variable presence during `docker exec`[0m

 Value /opt/rh/rh-nodejs14/root/usr/share/man is missing from variable MANPATH
MANPATH=/opt/rh/rh-python27/root/usr/share/man:/opt/rh/python27/root/usr/share/man:/opt/rh/httpd24/root/usr/share/man:/opt/rh/rh-nodejs14/root/usr/share/man

[1m[INFO] Checking if all scl variables are defined in Dockerfile[0m

[phracek]

RHEL7 test failed here:

08:50:02                 out:  [PASSED] for 'app' test_scl_usage
08:50:02                 out:  [PASSED] for 'app' test_connection
08:50:02                 out:  [PASSED] for 'app' test_docker_run_usage
08:50:02                 out:  [FAILED] for 'app' test_scl_variables_in_dockerfile
08:50:02                 out:  [PASSED] for 'app' test_npm_functionality
08:50:02                 out:  [PASSED] for 'app' test_npm_cache_cleared

08:39:51                 out: 
08:39:51                 out: [INFO] Running test test_scl_variables_in_dockerfile .......
08:39:51                 out: 
08:39:51                 out: Testing npm availability in Dockerfile
08:39:51                 out: 
                    Sending build context to Docker daemon 2.048 kB

08:39:51                 out: Step 1/2 : FROM rhscl/nodejs-14-rhel7:1
08:39:51                 out:  ---> 5ac5d773b0df
08:39:51                 out: Step 2/2 : RUN command -v npm | grep "^/opt/rh"
08:39:51                 out:  ---> Running in 984da1c20b29
08:39:51                 out: 
08:39:51                 out: /opt/rh/rh-nodejs14/root/usr/bin/npm
08:39:51                 out:  ---> a226d6d877e0
08:39:51                 out: Removing intermediate container 984da1c20b29
08:39:51                 out: Successfully built a226d6d877e0
08:39:51                 out: 
08:39:51                 out: [INFO] Testing variable presence during `docker exec`...
08:39:51                 out: 
08:39:52                 out:  Value /opt/rh/rh-nodejs14/root/usr/share/man is missing from variable MANPATH
08:39:52                 out: MANPATH=/opt/rh/rh-nodejs14/root/usr/share/man
08:39:52                 out: S2I image 'rhscl/nodejs-14-rhel7:1' test FAILED (exit code: 1)