Issue #3608148: Rename orchestra_webform_example to orchestra_interaction_webform_examples and nest it

Renames the example module and nests it under the module it demonstrates.

orchestra_webform_example (singular, top-level) ships more than one example (two request-validation webforms and two workflows) and is really an example of the Webform integration, so it should be plural and parent-prefixed and live under that module, matching the project's convention (as yoyaku_orchestra_example nests under yoyaku_orchestra).

What changed

• Machine name, human-readable name, .info.yml filename, PHP and test namespaces (Drupal\orchestra_interaction_webform_examples, Drupal\Tests\orchestra_interaction_webform_examples), the shipped configs' dependencies.enforced.module, the interface-translation project and its .po Project-Id-Version, and the docs references.
• Moved to modules/orchestra_interaction_webform/modules/orchestra_interaction_webform_examples/; the interface translation server pattern now points at the nested path.

Upgrade note

Pre-release, so no update path ships. A site with the old module enabled must migrate it in place before the next cache rebuild: rename the entry in core.extension, the system.schema and locale.project key-value entries, and the dependent config entities' stored dependencies, length-prefix-aware on the serialized values. A fresh install needs none of this.

Fixes #3608148.