Add geomGetLongestSurroundingRectangle and rename SSR type

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Summary

Adds geomGetLongestSurroundingRectangle alongside the existing geomGetSmallestSurroundingRectangle, and renames the SSR interface to SurroundingRectangle.

Changes

• New function: geomGetLongestSurroundingRectangle — returns the surrounding rectangle whose longest side is maximized. This may result in generating a more intuitive bounding box around features with a dominant axis (like buildings), and may be useful for placing labels and icons aligned to a building's dominant axis.
• Renamed type: SSR → SurroundingRectangle for clarity.
• Shared implementation: Both functions delegate to a generalized getSurroundingRectangle helper, differing only in their scoring strategy.
• Angle deduplication: Candidate angles are deduplicated via a Set keyed on Math.round(angle / ANGLE_EPSILON), avoiding testing of redundant rotations.
• Loop optimization: Replaced reduce with a for...of loop for extent accumulation; inlined rotation math to avoid allocating a temporary rotated-polygon array.
• Tests: Added real off-axis L-shaped building fixture (offAxisLShapedBuildingPoints) and assertions verifying both functions choose the correct envelope orientation.

Closes #267
Closes facebook/Rapid#1045