Add geofence function

[lognaturel]

Description

XForms spec: https://getodk.github.io/xforms-spec/#fn:geofence
JavaRosa implementation: https://github.com/getodk/javarosa/blob/d686d1bc985859f5a2789178fc32ea3595dfe316/src/main/java/org/javarosa/xpath/expr/XPathFuncExpr.java#L500
JavaRosa tests: https://github.com/getodk/javarosa/blob/d686d1bc985859f5a2789178fc32ea3595dfe316/src/test/java/org/javarosa/xpath/test/XPathEvalTest.java#L265

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Checklist

• Does it need UI/UX design?
  • Yes. Describe the UI/UX requirements or attach a Figma link in the "Design" section.
  • No
• Does it need API design?
  • Yes. Specify the endpoints, methods, or data structures needed.
  • No
• Does it need design around state flow?
  • Yes. Outline the state flow requirements.
  • No
• Does it need a test plan?
  • Yes. Add the test plan as a comment in this task or attach the document.
  • No

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User Stories

• As a [user type],
  I want [functionality],
  so that [benefit].

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Design

• Figma: [Insert URL]
• Design Docs: [Insert URL]

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Dependencies

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Additional Notes

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Related Issues