Simplify FixedSizeBinaryBuilder

[HaoYang670]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Currently, the FixedSizeBinaryBuilder is built on FixedSizeListBuilder, which introduce some extra computation(create child array, cast from listarray to binary array). We could simplily it by just using 2 buffer builders (not tested):

pub struct FixedSizeBinaryBuilder {
    values_builder: BufferBuilder<UInt8Type>,
    bitmap_builder: BooleanBufferBuilder,
    value_length: i32,
}

This may introduce just a little more code, but could save some amount of computation.

Describe alternatives you've considered
We could not do this.

Additional context
Add any other context or screenshots about the feature request here.