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ARROW-8777: [Rust] Parquet.rs does not support reading fixed-size binary fields.

Fixed length binary fields require some extra context to be passed to
the data conversion functions; the byte width of the data field.

This change also adds more specific converters for reading timestamp
types into Arrow. Previously an error would be raised because the schema
type (ie: Timestamp(Microseconds, _)) was different than the
converter-generated column type (UInt64).

Closes #7159 from maxburke/rust_fixed_len_array_reader

Authored-by: Max Burke <max@urbanlogiq.com>
Signed-off-by: Neal Richardson <neal.p.richardson@gmail.com>