feat(proxy-backend): configure request body revival for all targets

Signed-off-by: Dan Hoizner <dan.hoizner@gmail.com>

.changeset/ten-tigers-marry.md

@@ -0,0 +1,16 @@
+---
+'@backstage/plugin-proxy-backend': patch
+---
+
+The proxy-backend plugin now supports reviving request bodies that have previously been consumed by an express middleware (e.g. `express.json()`). This is done by setting `reviveConsumedRequestBodies: true` on the proxy `RouterOptions`. In order to preserve the current behavior, the proxy will **not** revive request bodies by default.
+
+The following is an example of a proxy `createRouter` invocation that revives request bodies:
+
+```diff
+const router = await createRouter({
+  config,
+  logger,
+  discovery,
++ reviveConsumedRequestBodies: true,
+});
+```