Revamp dbt-tap-gitlab: Update existing models and add more transformed models

Update existing models and add new transform models:

• Update gitlab_issues:

  1. Add newly tracked {assignees, closed_by_id, closed_at} attributes.

  2. Add {state_open_issues, state_closed_issues} to use in aggregates to count total open and closed issues.

  3. Add Date parts for easy grouping in Meltano Analyze

     • {created_day, created_week, created_month, created_quarter, created_year}

     • {closed_day, closed_week, closed_month, closed_quarter, closed_year}

  4. Add time to close metrics: `{time_to_close, hours_to_close, days_to_close}

  5. Add time tracking stats {time_estimate, total_time_spent, human_time_estimate, human_total_time_spent}

• Update gitlab_merge_requests:

  1. Add newly tracked {assignees, merged_at, closed_at} attributes.

  2. Add {state_open_mrs, state_closed_mrs, state_merged_mrs} to use in aggregates to count total open, merged and closed MRs.

  3. Add Date parts for easy grouping in Meltano Analyze

     • {created_day, created_week, created_month, created_quarter, created_year}

     • {closed_day, closed_week, closed_month, closed_quarter, closed_year}

     • {merged_day, merged_week, merged_month, merged_quarter, merged_year}

  4. Add time to close metrics: `{time_to_close, hours_to_close, days_to_close}

  5. Add time to merge metrics: `{time_to_merge, hours_to_merge, days_to_merge}

  6. Add time tracking stats {time_estimate, total_time_spent, human_time_estimate, human_total_time_spent}

• Add new model gitlab_labels that integrates the gitlab_group_labels and gitlab_project_labels in one table

• Update the gitlab_issues_per_label and gitlab_merge_requests_per_label to use the newly introduced gitlab_labels model

• Update gitlab_stats_per_user to also calculate total_assigned_issues_closed and total_authored_mrs_merged

• Add new model gitlab_stats_merged_mrs_per_month to calculate and store the total_mrs, total_authors, mrs_per_author and days_to_merge per project and month the MR was merged.

• Add new model gitlab_stats_per_project to calculate and store various issue and MR statistics per project and milestone.

• Add new model gitlab_stats_per_label to calculate and store various issue and MR statistics per label, project and milestone.

Closes #3 (closed)