restructure application, add get endpoint

internal/application/handlers.go

@@ -0,0 +1,19 @@
+package application
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+func (a *Application) GetClaimsHandler(c *gin.Context) {
+	system := c.DefaultQuery("system", "upc")
+	barcode := c.Query("barcode")
+
+	productClaims, err := a.GetClaims(system, barcode)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, nil)
+		return
+	}
+	c.JSON(http.StatusOK, productClaims)
+}