Add `get_public_key` for `StrongholdStorage` #4816

Job	Run time
check-for-run-condition	1s
check-for-modification	7s
build-wasm / build-wasm (ubuntu-latest)	3m 11s
build-and-test (ubuntu-latest)	15m 44s
build-and-test (macos-latest)	11m 39s
build-and-test (windows-latest)	13m 52s
test-wasm (ubuntu-latest)	4m 29s
	49m 3s

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