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ARROW-11361: [Rust] Build MutableBuffer/Buffer from iterator of bools

create a from_iter implementation for Buffer to collect boolean flags into a buffer that will:
* pre-allocate the appropriate size based on iterator site_hint()
* 'buffer' a byte in-memory until it's complete (at which point it is written)

Closes #9304 from tyrelr/buffer_from_iter_bool

Authored-by: Tyrel Rink <44035897+tyrelr@users.noreply.github.com>
Signed-off-by: Jorge C. Leitao <jorgecarleitao@gmail.com>