examples/rust: Update for new API additions

Update the echo-request and upload-reflector examples for the new
uwr_http_add_header_content_type() and uwr_http_add_header_content_len()
functions.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

Author: ac000

examples/rust/echo-request/src/lib.rs

@@ -102,12 +102,8 @@ pub extern "C" fn uwr_request_handler(addr: *mut u8) -> i32 {
     // storing the response headers at the beginning of our shared
     // memory at offset 0.
     uwr_http_init_headers(ctx, 2, 0);
-    uwr_http_add_header(ctx, "Content-Type", "text/plain");
-    uwr_http_add_header(
-        ctx,
-        "Content-Length",
-        &format!("{}", uwr_get_response_data_size(ctx)),
-    );
+    uwr_http_add_header_content_type(ctx, "text/plain");
+    uwr_http_add_header_content_len(ctx);
 
     // This calls nxt_wasm_send_headers() in Unit
     uwr_http_send_headers(ctx);

examples/rust/upload-reflector/src/lib.rs

@@ -49,7 +49,7 @@ pub fn upload_reflector(ctx: *mut luw_ctx_t) -> i32 {
         }
 
         uwr_http_init_headers(ctx, 2, 0);
-        uwr_http_add_header(ctx, "Content-Type", ct);
+        uwr_http_add_header_content_type(ctx, ct);
         uwr_http_add_header(
             ctx,
             "Content-Length",