Add support for iTwin Geospatial Features API

[jjspace]

Description

• Adds initial support for the OGC WFS Geospatial Features API through ITwinData.loadGeospatialFeatures
• Updates the iTwin Feature Service Sandcastle to use the new API

Issue number and link

No issue, follow up for #12344

Testing plan

• Load the iTwin Feature Service sandcastle and make sure it still works

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with a short summary of my change
• I have added or updated unit tests to ensure consistent code coverage
• I have updated the inline documentation, and included code examples where relevant
• I have performed a self-review of my code

[github-actions]

Thank you for the pull request, @jjspace!

✅ We can confirm we have a CLA on file for you.

[ggetz]

Thanks @jjspace! Code looks good to me!

It looks like CI is failing, could you please double check that?

[jjspace]

@ggetz fixed, should be good now, silly little issue with too many / with the debug pragma 🤦

[ggetz]

Thanks @jjspace! Code all looks good. I'll merge once we have confirmation about the dataset.

[ggetz]

@jjspace In the Sandcastle example, could you please update the points id to use 2380dc1b-1dac-4709-aa5c-f6cb38c4e9f5? After that, this should be good to go!

[jjspace]

@ggetz done, looks good