Add reverse geocoding for brewery street addresses (#245)

* Add geocoding to seed application, remove postal codes from generator

Update comments

tooling/pipeline/includes/biergarten_pipeline_orchestrator/coords.h

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+#ifndef BIERGARTEN_PIPELINE_INCLUDES_BIERGARTEN_PIPELINE_ORCHESTRATOR_COORDS_H_
+#define BIERGARTEN_PIPELINE_INCLUDES_BIERGARTEN_PIPELINE_ORCHESTRATOR_COORDS_H_
+
+/**
+ * @file biergarten_pipeline_orchestrator/coords.h
+ * @brief Shared coordinate jitter helper used to place generated
+ * brewery/user addresses near a city's centre.
+ */
+
+#include <cmath>
+#include <numbers>
+#include <random>
+
+namespace biergarten_pipeline_orchestrator_internal {
+
+struct Coords {
+   double longitude;
+   double latitude;
+};
+
+inline constexpr double kEarthRadiusKm = 6371.0;
+
+inline double DegreesToRadians(double degrees) {
+   return degrees * std::numbers::pi / 180.0;
+}
+
+inline double RadiansToDegrees(double radians) {
+   return radians * 180.0 / std::numbers::pi;
+}
+
+/**
+ * @brief Samples a point uniformly at random within @p distance_km of
+ * @p centre.
+ */
+inline Coords GetRandomCoordsWithinRange(const Coords& centre,
+                                         const int distance_km,
+                                         std::mt19937& rng) {
+   std::uniform_real_distribution<double> angle_dist(0.0,
+                                                     2.0 * std::numbers::pi);
+   std::uniform_real_distribution<double> unit_dist(0.0, 1.0);
+
+   const double angle_radians = angle_dist(rng);
+   // sqrt() keeps points uniformly distributed over the disc's area.
+   const double radius_km = distance_km * std::sqrt(unit_dist(rng));
+
+   const double delta_latitude_degrees =
+       RadiansToDegrees(radius_km * std::cos(angle_radians) / kEarthRadiusKm);
+   const double delta_longitude_degrees = RadiansToDegrees(
+       radius_km * std::sin(angle_radians) /
+       (kEarthRadiusKm * std::cos(DegreesToRadians(centre.latitude))));
+
+   return Coords{.longitude = centre.longitude + delta_longitude_degrees,
+                 .latitude = centre.latitude + delta_latitude_degrees};
+}
+
+}  // namespace biergarten_pipeline_orchestrator_internal
+
+#endif  // BIERGARTEN_PIPELINE_INCLUDES_BIERGARTEN_PIPELINE_ORCHESTRATOR_COORDS_H_