Rust IPC Read should be able to read V4 UnionType Array

[viirya]

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

At IPC reader, we assume no validity buffer for UnionType array. But on in V4 message, only null types have no validity bitmap. We should follow C++ IPC reader to read and skip the validity buffer for V4 message.

C++ IPC Reader:
https://github.com/apache/arrow/blob/c715bebbd89089f385c9996560866da23ea1ddda/cpp/src/arrow/ipc/reader.cc#L262-L277
https://github.com/apache/arrow/blob/91e3ac53e2e21736ce6291d73fc37da6fa21259d/cpp/src/arrow/ipc/metadata_internal.cc#L108-L113

Currently, the Rust IPC reader cannot read V4 UnionType array.
Follow the integration document, then run interop test against 0.17.1 golden file:

archery integration --with-cpp=true --with-rust=true --gold-dirs=/path/to/arrow/testing/data/arrow-ipc-stream/integration/0.17.1

The error is:

RuntimeError: Command failed: /Users/liangchi/repos/arrow/rust/target/debug/arrow-json-integration-test --integration --arrow=/Users/liangchi/repos/arrow/testing/data/arrow-ipc-stream/integration/0.17.1/generated_union.arrow_file --json=/var/folders/60/w6p4p5tj64ndcfnq0wzc38580000gn/T/tmpc24ewf3_/0.17.1_union.gold.json --mode=VALIDATE
With output:
--------------
thread 'main' panicked at 'range end index 11 out of range for slice of length 0', library/core/src/slice/index.rs:73:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Describe the solution you'd like
The interop test should be passed.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
#1404