Add `clear()` to `StorageKey` api #16838

Job	Run time
build-forc-doc-sway-lib-std	2m 1s
build-forc-test-project	5m 10s
build-mdbook	4m 58s
build-reference-examples	1m 9s
build-sway-lib-core	1m 1s
build-sway-examples	1m 16s
build-sway-lib-std	1m 9s
cargo-build-workspace	3m 13s
cargo-clippy	54s
cargo-fmt-check	18s
cargo-run-e2e-test	16m 15s
cargo-run-e2e-test-evm	2m 31s
cargo-run-e2e-test-midenvm	2m 27s
cargo-test-lib-std	4m 51s
cargo-test-workspace	7m 14s
cargo-toml-fmt-check	14s
cargo-unused-deps-check	8m 47s
forc-fmt-check-panic	1m 28s
forc-fmt-check-sway-examples	53s
forc-pkg-fuels-deps-check	20s
forc-run-benchmarks	2m 30s
forc-unit-tests	1m 32s
pre-publish-check	0s
notify-slack-on-failure	3s
build-publish-master-image	0s
publish	0s
build-publish-release-image	0s
Build and upload forc binaries to release	0s
	1h 10m 14s

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