Add the blip image captioning model (#1140)

* Blip text model.

* Blip vision bits.

* Blippity.

* More blip.

candle-transformers/src/models/mod.rs

@@ -1,5 +1,7 @@
 pub mod bert;
 pub mod bigcode;
+pub mod blip;
+pub mod blip_text;
 pub mod convmixer;
 pub mod dinov2;
 pub mod efficientnet;