[Stacked PR] [Based on #1206] [#301] Move 'Duration' files to 'iox2/bb'

[elBoberido]

Notes for Reviewer

This PR moves iox2/legacy/duration.hpp and its dependencies to iox2/bb/duration.hpp. Furthermore, the namespace is adjusted to iox2::bb and the clang-tidy warnings are fixed.

Pre-Review Checklist for the PR Author

• Add sensible notes for the reviewer
• PR title is short, expressive and meaningful
• Consider switching the PR to a draft (Convert to draft)
  • as draft PR, the CI will be skipped for pushes
• Relevant issues are linked in the References section
• Every source code file has a copyright header with SPDX-License-Identifier: Apache-2.0 OR MIT
• Branch follows the naming format (iox2-123-introduce-posix-ipc-example)
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  • Commit messages have the issue ID ([#123] Add posix ipc example)
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• Tests follow the best practice for testing
• Changelog updated in the unreleased section including API breaking changes
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Checklist for the PR Reviewer

• Commits are properly organized and messages are according to the guideline
• Unit tests have been written for new behavior
• Public API is documented
• PR title describes the changes

Post-review Checklist for the PR Author

• All open points are addressed and tracked via issues

References

Closes #

[elBoberido]

If it is okay, I would omit the additional unit namespace. It was always an outlier in iceoryx_hoofs and it was the only class in that namespace. No hard feelings about this and I will add it if desired.

[elBoberido]

The class was modeled after the Rust Duration but the naming of the methods is a bit off. I'd like to rename the to_ methods to as_. We have something similar with the SemanticString::as_string method.

Furthermore, I would like to shorten the name a little bit and use nanos, micros, etc. instead of nanoseconds, microseconds, etc. Also no hard feelings about this but if this change is not desired, I would rename the newly introduced subsec_nanos, etc. to subsecond_nanoseconds, etc. in order to have the same naming style.

The main reason for this is to get more code into one line without hitting the 120 character limit.