Draft: CLI for all steps of release

This MR ensures the following workflow

Create Milestone if not exists

$ gla project milestone create --pid 61260895 --title <milestone_title>

Get ids of closed issues not yet bound to milestone

$ gla project issue list --pid 61260895 --state closed --milestone None -s csv -i iid

Assign each of retrieved issues to milestone

$ gla project issue update --pid 61260895 --iid <issue_id> --milestone_id <milestone_id>

Create release

$ gla project release create --pid 68140149 --tag_name <tag_name> --description "$(gla project issue list --pid 61260895 --state closed --milestone <milestone_title> -s markdown -i iid,author,title)"

Closes #115