[20414] Bump version to 2.0.0

[JesusPoderoso]

Description

This PR:

• [x] Bumps version to 2.0.0 in consonance with eProsima/Fast-DDS#4439
• [x] Updates the mirror workflow to mirror master in 1.5.x
• [x] Adds this PR template
• [x] Ports the repository's colcon.meta from JSON to YAML

Contributor Checklist

• [x] Commit messages follow the project guidelines.
• N/A Code builds and tests pass locally.
• N/A Applicable backports have been included in the description.

Reviewer Checklist

• [x] The PR has a milestone assigned.
• [ ] The title and description correctly express the PR's purpose.
• [ ] Check contributor checklist is correct.
• [ ] CI passes without warnings or errors.