Synthetic Photochemistry. XXXIV. Synthetic Strategy of 5-8-5-Membered Tricyclic Higher Terpenoids Based on the Condensation of Two Optically-Active Iridoids, C10-Synthons Obtained from Photo-Cycloadduct of Methyl 2,4-Dioxopentanoate–Isoprene, and Its Application to a Synthesis of the Basic Carbon Skeleton of Fusicoccane