feat(compiler): add "original" placeholder value on extracted XMB (#25079)

Update XMB placeholders(<ph>) to include the original value on top of an
example. Placeholders can by definition have one example(<ex>) tag and a
text node. The text node is used by TC as the "original" value from the
placeholder, while the example should represent a dummy value.
For example: <ph name="PET"><ex>Gopher</ex>{{ petName }}</ph>.
This change makes sure that we have the original text, but it *DOES NOT*
make sure that the example is correct. The example has the same wrong
behavior of showing the interpolation text rather than a useful
example.

No breaking changes, but tools that depend on the previous behavior and
don't consider the full XMB definition may fail to parse the XMB.
Fixes b/72565847

PR Close #25079

packages/core/test/bundling/hello_world_r2/bundle.golden_symbols.json

@@ -1737,7 +1737,7 @@
     "name": "_ESCAPED_CHARS"
   },
   {
-    "name": "_EXEMPLE_TAG"
+    "name": "_EXAMPLE_TAG"
   },
   {
     "name": "_EmittedLine"
@@ -3839,4 +3839,4 @@
   {
     "name": "wtfLeave"
   }
-]
+]