IRIDL server-side processing

Server-side processing:

• select and aggregate lead_time L and forecast_time S
• regrid X and Y to 1.5 deg grid
• SubX intake catalog biweekly
• requires unreleased climetlab_s2s_ai_challenge plugin
• init frequency forecast: keep as todo
• IRIDL cat S2S
• IRIDL obs regrid
• check proper lead ints or floats to match my int lead_time

closes #9 (closed)