Add deprecation warnings for package-internal APIs #783

Job	Run time
build-eliza-cocoapods-example	1m 21s
build-eliza-swiftpm-example	3m 18s
build-library-macos	2m 53s
build-library-ios	2m 50s
build-library-tvos	2m 47s
build-library-watchos	2m 51s
build-plugin-and-generate	1m 0s
run-conformance-tests	2m 22s
run-swiftlint	10s
run-unit-tests	2m 19s
validate-license-headers	27s
	22m 18s

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