[arrow-avro] Enhance benchmark suite

**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**

The `arrow-avro` benchmark suite only covers a subset of the supported data-types and does not exercise the streaming writer.

Concretely:

- The crate’s **supported decode sites** are listed by `arrow_avro::reader::record::Decoder` (i.e., `TimestampNanos`, Arrow `Duration(*)`, `RunEndEncoded`, `Union`, `Decimal32/64/256`, etc.). These are not all covered by the current `benches/decoder.rs`.
- The crate’s **supported encode sites** are listed by `arrow_avro::writer::encoder::Encoder` (i.e., `Date32`, `Time32SecsToMillis`, `Time64Micros`, `Utf8View/BinaryView`, `ListView/LargeListView`, `FixedSizeList`, `RunEncoded16/32/64`, `Utf8Large/LargeBinary`, `TimestampMillis/Nanos`, etc.). These are not all covered by the current `benches/avro_writer.rs`.
- There is **no benchmark for `AvroStreamWriter`** even though the writer module exposes it for SOE streams (a common production path for registry‑based pipelines).

Additionally, `benches/decoder.rs` still relies on the external **`apache-avro`** crate to generate Avro bytes for the reader benchmarks. Now that `arrow-avro` has its own `AvroWriter`, we can remove this extra dependency entirely by using the in‑crate writer to generate input payloads for decode benches.

**Describe the solution you'd like**

1. **Extend benchmark coverage in `benches/decoder.rs` and `benches/avro_writer.rs`.** Based on the current `Decoder` / `Encoder` variants, by adding support for the following **types that are missing coverage**:
- **In decoder.rs, add benches for:**
- `Null`
- `TimestampNanos`
- Arrow **`Duration`** units: `DurationSecond`, `DurationMillisecond`, `DurationMicrosecond`, `DurationNanosecond`
- `Decimal32`, `Decimal64`, `Decimal256` (note: `Decimal128` is already exercised)
- `RunEndEncoded`
- `Union` (dense)
- All Schema resolution , i.e. `Int32ToFloat64`, etc.
- **In `avro_writer.rs`, add benches for:**
- `Null`
- **Date/Time/Timestamp:** `Date32`, `Time32SecsToMillis`, `Time32Millis`, `Time64Micros`, `TimestampMillis`, `TimestampNanos`
- **View & large‑offset types:** `Utf8View`, `BinaryView`, `Utf8Large`, `LargeBinary`
- **List variants:** `ListView`, `LargeListView`, `FixedSizeList`, `LargeList`
- **Run‑end encoded:** `RunEncoded16`, `RunEncoded32`, `RunEncoded64`
- **Intervals & Durations:** `IntervalYearMonth`, `IntervalDayTime`, `IntervalMonthDayNano` (if not already present), plus Arrow `DurationSeconds/Millis/Micros/Nanos`
- `Union` (dense)
2. **Add a new `benches/stream.rs` for `AvroStreamWriter`.** Create a new benchmark file that emits Avro **Single‑Object Encoding (SOE)** records for each supported type using `AvroStreamWriter`, and then decodes them with the `Decoder` to measure end‑to‑end streaming performance. This is a common production path when using a schema registry, and the writer docs explicitly call out `AvroStreamWriter`.
- Cover all the types listed above (mirroring the static writer benches), including nested (`Struct`, `Map`, `List*`, `Union`) and fixed/UUID/decimal/interval/duration sites.
- Include a small “mixed record” schema (several fields across categories) to reflect real‑world row composition.
3. **Remove `apache-avro` from the benches and rely on the in‑crate writer.** Refactor `benches/decoder.rs` to **generate input bytes with `arrow_avro::writer::AvroWriter` (OCF)** instead of the external `apache-avro` crate, and drop that dev‑dependency from the crate entirely. This makes the benches self‑contained and tests precisely the Arrow‑native encode/decode paths.

**Describe alternatives you've considered**

- **Status quo**: Keep partial coverage in two benches. This leaves gaps for correctness/perf regressions (i.e., nano‑precision timestamps, Arrow `Duration(*)`, REE/Union sites) and misses the streaming path entirely.
- **Only unit tests**: Unit tests validate correctness but don’t capture micro‑perf characteristics or regressions across serialization choices (i.e., offset widths, view vs. non‑view, REE). Benchmarks give actionable signals over time.

**Additional context**

N/A

Start with benches/decoder.rs and benches/avro_writer.rs, comparing their cases with the supported variants in arrow_avro::reader::record::Decoder and arrow_avro::writer::encoder::Encoder. Read the AvroWriter and AvroStreamWriter APIs, then run the existing benchmark targets before adding benches/stream.rs. Done means the listed types and mixed streaming record are covered, decoder inputs use the in-crate writer, and the apache-avro bench dependency is removed.

Written by the indexing model from the issue text.