Remove from_trusted_len_* from Buffer

[jorgecarleitao]

This PR proposes to remove some functions from Buffer since there are more idiomatically achieved with Vec's API.

Specifically, the following are equivalents

• Buffer::new_zeroed(length) <-> vec![0; length].into()
• Buffer::from_slice(slice) <-> slice.to_vec().into()
• Buffer::from_trusted_len_iter(iter) <-> iter.collect::<Vec<_>>().into()
• Buffer::try_from_trusted_len_iter(iter) <-> iter.collect::<Result<Vec<_>>>()?.into()

This allows the API and documentation of Buffer to focus on its main semantics:

• O(1) slicing
• copy on write

[codecov]

Codecov Report

Merging #1020 (52af809) into main (e976c1e) will increase coverage by 0.00%.
The diff coverage is 85.71%.

@@           Coverage Diff           @@
##             main    #1020   +/-   ##
=======================================
  Coverage   71.63%   71.64%           
=======================================
  Files         359      359           
  Lines       19904    19893   -11     
=======================================
- Hits        14259    14252    -7     
+ Misses       5645     5641    -4     

Impacted Files	Coverage Δ
src/array/map/mod.rs	64.19% <0.00%> (ø)
src/array/mod.rs	67.02% <ø> (ø)
src/buffer/immutable.rs	97.77% <ø> (+4.92%)	⬆️
src/array/binary/mod.rs	84.46% <100.00%> (ø)
src/array/fixed_size_binary/mod.rs	88.34% <100.00%> (ø)
src/array/list/mod.rs	69.91% <100.00%> (ø)
src/array/primitive/mod.rs	78.63% <100.00%> (ø)
src/array/union/mod.rs	79.64% <100.00%> (ø)
src/array/utf8/mod.rs	73.40% <100.00%> (ø)
src/bitmap/utils/slice_iterator.rs	87.93% <0.00%> (+1.72%)	⬆️

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