feat(REST): allow to return full WKT definition for CRS definition endpoint

NOTE: Should be improved to ask either WKT v1 or v2.

Author: alexismanin

src/main/java/com/geomatys/crsservice/rest/CRSOperationController.java

@@ -54,7 +54,7 @@ public CRSOperationController(CrsOperationService service) {
     @CrossOrigin
     @RequestMapping(path = "define", method = RequestMethod.GET)
     @Parameter(name = "source", example = "EPSG:3395")
-    @Parameter(name = "format", schema = @Schema(type = "string", allowableValues = {"application/json"}))
+    @Parameter(name = "format", schema = @Schema(type = "string", allowableValues = {"application/json", "application/wkt"}))
     public ResponseEntity<Resource> getCRS(
                                  @RequestParam String source,
                                  @RequestParam(required = false, defaultValue = "false") boolean longitudeFirst,

src/main/java/com/geomatys/crsservice/service/DefaultCrsOperationService.java

@@ -97,7 +97,10 @@ public SourceCode getCRS(CRSParameters request) throws IllegalArgumentException,
             );
 
         } else if (FORMAT_WKT.equals(format)) {
-            throw new UnsupportedOperationException("TODO");
+            return new SourceCode(
+                    MediaType.parseMediaType(FORMAT_WKT + "; charset=utf-8"),
+                    new ByteArrayResource(crs.toWKT().getBytes(StandardCharsets.UTF_8))
+            );
         } else {
             throw new IllegalArgumentException("Format not supported " + format);
         }