feat(actionsRegistry): Adding support for examples (#33551)

* feat(backend-plugin-api): add typed examples to actions registry

Signed-off-by: benjdlambert <ben@blam.sh>

* fix: address review feedback for actions registry examples

Signed-off-by: benjdlambert <ben@blam.sh>

* fix: remove empty examples from scaffolder action bridge

Signed-off-by: benjdlambert <ben@blam.sh>

* chore: add changeset for scaffolder-backend

Signed-off-by: benjdlambert <ben@blam.sh>

* fix: update router test to match removed examples field

Signed-off-by: benjdlambert <ben@blam.sh>

---------

Signed-off-by: benjdlambert <ben@blam.sh>

.changeset/add-actions-registry-examples.md

@@ -0,0 +1,7 @@
+---
+'@backstage/backend-plugin-api': minor
+'@backstage/backend-defaults': patch
+'@backstage/backend-test-utils': patch
+---
+
+Added support for typed `examples` on actions registered via the actions registry. Action authors can now provide examples with compile-time-checked `input` and `output` values that match their schema definitions.

.changeset/remove-empty-examples-scaffolder-bridge.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-scaffolder-backend': patch
+---
+
+Removed unnecessary empty `examples` array from actions bridged via the actions registry.