Siri: add AppIntentVocabulary.plist

Submission to iTunes generates warnings like:
`Invalid Siri Support - No example phrase was provided for INSendMessageIntent in the "en" language`

Such warnings seem legitimate for end users.

doc: https://developer.apple.com/documentation/sirikit/registering_custom_vocabulary_with_sirikit/global_vocabulary_reference?language=objc

Start by reviewing the Apple SiriKit global vocabulary reference linked in the issue and locating where AppIntentVocabulary.plist belongs in the iOS app. Add the vocabulary entry for INSendMessageIntent with an English example phrase, then verify that an iTunes submission no longer reports the missing example-phrase warning.

Written by the indexing model from the issue text.