Read dictionary from nested struct in ipc stream reader panics

[dispanser]

Describe the bug
We have an application that reads ipc stream data, and it panicked while reading a record batch that contains a dictionary in a nested struct:

   0: rust_begin_unwind
             at /rustc/9d1b2106e23b1abd32fce1f17267604a5102f57a/library/std/src/panicking.rs:498:5
   1: core::panicking::panic_fmt
             at /rustc/9d1b2106e23b1abd32fce1f17267604a5102f57a/library/core/src/panicking.rs:116:14
   2: core::panicking::panic_bounds_check
             at /rustc/9d1b2106e23b1abd32fce1f17267604a5102f57a/library/core/src/panicking.rs:84:5
   3: arrow::ipc::reader::read_dictionary
             at /home/pi/src/github/dispanser/arrow-rs/arrow/src/ipc/reader.rs:573:13
   4: arrow::ipc::reader::StreamReader<R>::maybe_next
             at /home/pi/src/github/dispanser/arrow-rs/arrow/src/ipc/reader.rs:983:17
   5: <arrow::ipc::reader::StreamReader<R> as core::iter::traits::iterator::Iterator>::next
             at /home/pi/src/github/dispanser/arrow-rs/arrow/src/ipc/reader.rs:1004:9

This is caused by an incorrectly sized dictionaries_by_field in the stream reader. PR is ready, opening this for tracking purposes.

To Reproduce

Create a record batch containing a nested struct with a dictionary in last position, write to IPC and attempt to read back using ipc::reader::StreamReader.

Expected behavior

A record batch instead of a panic :)