Adds triage workflow.

[francocipollone]

Part of https://github.com/maliput/.github/issues/2

Summary

• Adds triage workflow por adding automatically new issues and prs to https://github.com/orgs/maliput/projects/1

Resuable workflow added at: https://github.com/maliput/.github/pull/3

[francocipollone]

Working correctly