Add separate rules for Merge Request pipeline and branch pipeline

• GitLab CI on default runs CI pipeline separate for branch (aka branch pipeline) and MR (aka Merge Request pipeline)
• Current templates supports only Merge Request pipeline to avoid duplication with branch pipeline
• It is possible to add rules with GitLab CI environment variables to enable Merge Request pipeline only for MR and branch pipeline when no MR is created
• rules:if
• Predefined variables reference