Add custom location provider example

[ZiZasaurus]

Create an example to showcase creating a custom location provider in v10.

Pull request checklist:

• Write tests for all new functionality. If tests were not written, please explain why.
• Add documentation comments for any added or updated public APIs.
• Add any new public, top-level symbols to the Jazzy config's custom_categories (scripts/doc-generation/.jazzy.yaml)
• Describe the changes in this PR, especially public API changes.
• Add a changelog entry to to bottom of the relevant section (typically the ## main heading near the top).
• Update the guides (internal access only), README.md, and DEVELOPING.md if their contents are impacted by these changes.
• Review and agree to the Contributor License Agreement (CLA).