Data models publishing pipeline

This merge request add the pipeline for publish data models to https://test.uncefact.org/vocabulary/untp/ in machine- and human-readable formats.

The pipeline file is named untp-data-models-publish.yml. It includes the following jobs:

1. prepare - determines the version to publish (working or the release one), checks the data models if they need to be excluded from the publishing in case of the working version.
2. generate - generates md and json files for jekyll website using vocab-jsonld-utility-1.6.5.jar utility
3. jekyll_build - runs jekyll build and creates _site directory for the publication with html pages and artefacts to publish
4. assume_role - assumes AWS role with the GitLab web identity, saves AWS session credentials to the .env file
5. data-models-publish - updates the s3 bucket in AWS account using AWS credentials obtained in assume_role

for now aws s3 sync is run with --dryrun option - we want to test it first for both working(snapshot) and a release candidate versions.

Also this PR adds untp-cvc data-model and jargon action type release to process webhooks from jargon for releases. It creates a PR the same as for the snapshots, but with another commit message, MR title, MR body and branch name.

TODO:

1. we need to update versions files in the repo with a new version when a release is created - we need to automate this
2. home page needs to be updated when a release is created - https://test.uncefact.org/vocabulary/untp/home - we need to automate this as well