refactor(runtimes): add move the OCaml runtime into runtimes/ocaml

compiler/dune

@@ -14,14 +14,6 @@
   verification)
  (modules plugin driver))
 
-(library
- (name runtime)
- (public_name catala.runtime)
- (preprocess
-  (pps ppx_yojson_conv))
- (libraries calendar zarith zarith_stubs_js)
- (modules runtime))
-
 (executable
  (name catala_web_interpreter)
  (modes byte js)

dune

@@ -1,4 +1,4 @@
-(dirs compiler french_law build_system)
+(dirs runtimes compiler french_law build_system)
 
 (data_only_dirs tests examples syntax_highlighting)
 

runtimes/ocaml/dune

@@ -0,0 +1,7 @@
+(library
+ (name runtime)
+ (public_name catala.runtime)
+ (preprocess
+  (pps ppx_yojson_conv))
+ (libraries calendar zarith zarith_stubs_js)
+ (modules runtime))