ci: add a release job

Overview

This MR introduces a new GitLab CI job for releasing the CLI binary.

Creating a new token

For creating releases, I generated a project access token with api scope (full access) and maintainer role. I added this token as GITLAB_TOKEN_RELEASE protected variable to the CI Variables config. I tried to use developer role, but it wasn't enough to create a release.

Related Issue

Related to #1014 (closed)

How Has This Been Tested?

• I've run the new release job on a tag https://gitlab.com/viktomas/cli/-/pipelines/565451038
• I've run the new release job on a normal branch https://gitlab.com/viktomas/cli/-/pipelines/565430144
• Running the new release job on a tag produces a GitLab release: https://gitlab.com/viktomas/cli/-/releases/v1.22.4

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation
• Chore (Related to CI or Packaging to platforms)