Release Configuration in .yml + Job Token for release generation from .yml
### Problem to solve
Now that we have a releases page (https://gitlab.com/gitlab-org/gitlab-ce/issues/41766), there should be a straightforward way to create a release from the `.gitlab-ci.yml` without making curls to the [Releases API](https://docs.gitlab.com/ee/api/releases/index.html). This issue will just support the release configuration not generation.
### Target audience
Automation engineers who are working on releases and want a native way to add releases without using `script:` elements to curl an API
### Further details
This is good polish for the releases feature in that it makes the integration feel better integrated into the product. Also, this provides better overall experience once features like https://gitlab.com/gitlab-org/gitlab-ce/issues/56023 are implemented.
### Proposal
Build release configuration in yml:
```yaml
stages:
- build
- test
- release
release:
stage: release
only: tags
script:
- make changelog | tee release_changelog.txt
release:
name: Release $CI_TAG_NAME
description: ./release_changelog.txt
assets:
links:
- name: cool-app.zip
url: http://my.awesome.download.site/1.0-$CI_COMMIT_SHORT_SHA.zip
- url: http://my.awesome.download.site/cool-app.exe
```
These keys and links will be built in this iteration and exposed via the API. Binary Assets will be supported in a follow-up issue https://gitlab.com/gitlab-org/gitlab/issues/36133
- `release:assets` adds assets to the release.
- `release:assets:links` an array of link-type assets
- `release:assets:links:name` (optional) specifies the asset name as an improvement over a raw url
- `release:assets:links:url` specifies a link to the asset, which is stored externally and pre-created or created by `script`.
Uploading of binary or packaged assets into object storage or the GitLab Package repository are not supported by this iteration.
See also the [proposed documentation](https://gitlab.com/gitlab-org/gitlab/merge_requests/19237/diffs)
issue