Render fallback crystal portals as two-sided surfaces

src/main/resources/assets/rivencraft/blockstates/crystal_portal.json

@@ -1 +1 @@
-{"variants":{"live_view=false":{"model":"rivencraft:block/crystal_portal"},"live_view=true":{"model":"rivencraft:block/crystal_portal"}}}
+{"variants":{"axis=x,live_view=false":{"model":"rivencraft:block/crystal_portal","y":90},"axis=x,live_view=true":{"model":"rivencraft:block/crystal_portal","y":90},"axis=y,live_view=false":{"model":"rivencraft:block/crystal_portal","x":90},"axis=y,live_view=true":{"model":"rivencraft:block/crystal_portal","x":90},"axis=z,live_view=false":{"model":"rivencraft:block/crystal_portal"},"axis=z,live_view=true":{"model":"rivencraft:block/crystal_portal"}}}

src/main/resources/assets/rivencraft/models/block/crystal_portal.json

@@ -1 +1 @@
-{"parent":"minecraft:block/cube_all","textures":{"all":"rivencraft:block/crystal_portal"}}
+{"textures":{"portal":"rivencraft:block/crystal_portal"},"elements":[{"from":[0,0,7.5],"to":[16,16,8.5],"shade":false,"faces":{"north":{"texture":"#portal"},"south":{"texture":"#portal"}}}]}