Rust

Fix strpos invocation with dictionary and null #253

Job	Run time
build with wasm-pack	2m 42s
cargo test (win64)	54m 12s
Check cargo fmt	40s
cargo check	10m 58s
cargo test (macos)	12m 11s
cargo test (macos-aarch64)	10m 44s
Verify MSRV (Min Supported Rust Version)	7m 5s
Verify Vendored Code	54s
cargo test datafusion-cli (amd64)	4m 5s
cargo test (amd64)	10m 22s
cargo doc	4m 2s
cargo test doc (amd64)	15m 15s
cargo examples (amd64)	13m 44s
Run sqllogictest with Postgres runner	3m 35s
verify benchmark results (amd64)	12m 21s
check Cargo.toml formatting	3m 13s
clippy	5m 52s
check configs.md is up-to-date	2m 56s
cargo test hash collisions (amd64)	14m 49s
cargo test pyarrow (amd64)	2m 54s
	3h 12m 34s

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