Show diff in codesize expectations CI job

[hoodmane]

I tried it here and it shows the following exactly as I wanted:

Details

Full diff from the current expectations to the rebaselined expectations:

diff --git a/test/codesize/test_codesize_files_js_fs.json b/test/codesize/test_codesize_files_js_fs.json
index 4e36e55..919b88c 100644
--- a/test/codesize/test_codesize_files_js_fs.json
+++ b/test/codesize/test_codesize_files_js_fs.json
@@ -1,10 +1,10 @@
 {
-  "a.out.js": 17871,
-  "a.out.js.gz": 7460,
+  "a.out.js": 17895,
+  "a.out.js.gz": 7467,
   "a.out.nodebug.wasm": 381,
   "a.out.nodebug.wasm.gz": 258,
   "total": 18276,
-  "total_gz": 7718,
+  "total_gz": 7725,
   "sent": [
     "a (fd_write)",
     "b (fd_read)",
diff --git a/test/codesize/test_codesize_hello_dylink_all.json b/test/codesize/test_codesize_hello_dylink_all.json
index 00cc3bd..0b513f9 100644
--- a/test/codesize/test_codesize_hello_dylink_all.json
+++ b/test/codesize/test_codesize_hello_dylink_all.json
@@ -1,5 +1,5 @@
 {
-  "a.out.js": 270695,
+  "a.out.js": 270707,
   "a.out.nodebug.wasm": 588098,
   "total": 858805,
   "sent": [