feat(array): add value_at_unchecked for Array

[ichn-hu]

What's changed and what's your intention?

PLEASE DO NOT LEAVE THIS EMPTY !!!

Please explain IN DETAIL what the changes are in this PR and why they are needed:

An unchecked version of value_at is added to the Array trait, and corresponding implementations are also added.

Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests

Refer to a related PR or issue link (optional)

close #1814

[CLAassistant]

All committers have signed the CLA.

[ichn-hu]

@TennyZhuang @skyzh PTAL

[TennyZhuang]

Generally LGTM, Thanks!

[codecov]

Codecov Report

Merging #2136 (aacaf1b) into main (a366da9) will decrease coverage by 0.01%.
The diff coverage is 62.12%.

@@            Coverage Diff             @@
##             main    #2136      +/-   ##
==========================================
- Coverage   70.58%   70.57%   -0.02%     
==========================================
  Files         650      650              
  Lines       82208    82266      +58     
==========================================
+ Hits        58030    58060      +30     
- Misses      24178    24206      +28     

Flag	Coverage Δ
rust	70.57% <62.12%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/common/src/array/chrono_array.rs	78.94% <0.00%> (-3.09%)	⬇️
src/common/src/array/decimal_array.rs	90.61% <0.00%> (-2.18%)	⬇️
src/common/src/array/list_array.rs	88.88% <0.00%> (-1.02%)	⬇️
src/common/src/array/struct_array.rs	80.43% <0.00%> (-1.27%)	⬇️
src/common/src/array/bool_array.rs	92.54% <50.00%> (-2.97%)	⬇️
src/common/src/array/mod.rs	70.95% <85.71%> (+0.28%)	⬆️
src/common/src/array/interval_array.rs	63.24% <88.88%> (+2.13%)	⬆️
src/common/src/array/data_chunk_iter.rs	85.30% <100.00%> (+0.26%)	⬆️
src/common/src/array/primitive_array.rs	90.81% <100.00%> (+0.25%)	⬆️
src/common/src/array/utf8_array.rs	93.47% <100.00%> (+0.16%)	⬆️
... and 3 more

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[ichn-hu]

@TennyZhuang resolved, PTAL again.

[TennyZhuang]

CI running https://github.com/singularity-data/risingwave/actions/runs/2237309996

[TennyZhuang]

LGTM! Thanks