feat: add implicit native coercion constructor (#24282)

## Which issue does this PR close?

- Closes #24135.

## Rationale for this change

When a coercion's desired type is a native logical type, callers
currently have to repeat that type as both
`TypeSignatureClass::Native(...)` and `default_casted_type`. This
duplication is confusing and can allow the two values to disagree.

## What changes are included in this PR?

- Add `Coercion::new_implicit_native`, which derives
`default_casted_type` from the desired logical type and delegates to the
existing `new_implicit` constructor.
- Keep `Coercion::new_implicit` unchanged for backward compatibility and
non-native desired type classes.
- Migrate the representative `reverse` and `approx_percentile_cont` call
sites linked from the issue.
- Update the `Coercion` rustdoc example and add a
constructor-equivalence unit test.

## Are these changes tested?

Yes:

- `cargo test -p datafusion-expr-common test_new_implicit_native --lib`
- `cargo test -p datafusion-functions reverse --lib`
- `cargo test -p datafusion-functions-aggregate approx_percentile_cont
--lib`
- `cargo test -p datafusion-expr-common --doc`
- `cargo clippy -p datafusion-expr-common -p datafusion-functions -p
datafusion-functions-aggregate --all-targets --all-features -- -D
warnings`
- `cargo fmt --all`

The required full-workspace `cargo clippy --all-targets --all-features
-- -D warnings` was also attempted on Windows. It reached an unrelated
MSVC native-link failure while building `protobuf-src`
(`LNK2005`/`LNK4098` in `protoc-gen-upb`); affected-crate clippy passed
with warnings denied, and CI will run the full Linux workspace checks.

No benchmark was run because this is an API convenience constructor that
delegates to the existing constructor and does not change runtime
execution.

## Are there any user-facing changes?

Yes. This adds the public `Coercion::new_implicit_native` convenience
API. It is additive and backward compatible; existing `new_implicit`
callers continue to work unchanged.

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Co-authored-by: jiangzhen <jiangzhen@nuanwa.net>