Add strategy-focused InList benchmarks (#21648)

## Which issue does this PR close?

- Part of #19241.
- This PR was originally proposed as the first commit in the broader `IN
LIST` optimization series in #19390.

## Rationale for this change

`IN LIST` has become the target of several specialized execution
strategies, but the existing benchmark coverage in
`datafusion/physical-expr/benches/in_list.rs` is mostly end-to-end and
historical in nature. That broad coverage is useful for regression
tracking, but it is not ideal for answering more focused questions such
as:

- how a specific strategy behaves as the list size crosses a threshold
- whether the fast path helps both hit-heavy and miss-heavy workloads
- how null handling affects the strategy-specific implementations
- how two-stage string filters behave in their worst-case collision
patterns

This PR adds a dedicated strategy benchmark harness for `IN LIST` so
future performance work can be evaluated against a stable, repeatable,
strategy-focused corpus.

This PR does not change `InList` execution behavior. It only adds
benchmark coverage.

## What changes are included in this PR?

- Adds `datafusion/physical-expr/benches/in_list_strategy.rs`
- Registers the new benchmark target in
`datafusion/physical-expr/Cargo.toml`
- Keeps the existing `benches/in_list.rs` benchmark suite intact for
broader historical comparison
- Adds targeted Criterion coverage for the main `IN LIST` strategy
families, including:
  - bitmap-style paths for narrow integer cases
- branchless and hash/probe-style paths for primitive values at
different list-size thresholds
  - reinterpretation-heavy cases such as floats and timestamps
- string and string-view cases, including stage-2 / prefix-collision
stress inputs
  - null-heavy and `NOT IN` scenarios
- dictionary and fixed-size-binary coverage used by the broader `IN
LIST` implementation

## Are these changes tested?

Yes. I validated this PR with:

- `cargo fmt --all`
- `cargo clippy -p datafusion-physical-expr --all-targets --all-features
-- -D warnings`
- `cargo test -p datafusion-physical-expr in_list --lib`

## Are there any user-facing changes?

No user-facing changes. This PR only adds benchmark coverage for
development and performance evaluation.

Author: geoffreyclaude

datafusion/physical-expr/Cargo.toml

@@ -71,6 +71,10 @@ rstest = { workspace = true }
 harness = false
 name = "in_list"
 
+[[bench]]
+harness = false
+name = "in_list_strategy"
+
 [[bench]]
 harness = false
 name = "case_when"