add HDPE water pipeline and water booster pump

[doneachh]

Closes # (if applicable).

Changes proposed in this Pull Request

Adding costs for HDPE water pipelines and pumps -> needed for integration of desalination and water management in pypsa-earth

Checklist

• Code changes are sufficiently documented; i.e. new functions contain docstrings and further explanations may be given in doc.
• Data source for new technologies is clearly stated.
• Newly introduced dependencies are added to environment.yaml (if applicable).
• A note for the release notes doc/release_notes.rst of the upcoming release is included.
• I consent to the release of this PR's code under the GPLv3 license.

[doneachh]

Hi @euronion :)
are you able to review this. I would need it for this PR: pypsa-meets-earth/pypsa-earth#1858
Thanks a lot.

[euronion]

Yes, I'll review. Next time feel free to ping me with the PR as soon as you feel like it is ready for review. :)

[euronion]

Thanks for the contribution, see the comments below and let me know if you have any question!

[doneachh]

@euronion sorry for taking so long to get back to you - I tried to resolve all your comments, please review and feel free to ping me if something should be handled differently. Thanks :)