ARROW-17899: [Go][CSV] Add Decimal support to CSV reader

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CC @mitchdevenport

[github-actions[bot]]

https://issues.apache.org/jira/browse/ARROW-17899

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Benchmark runs are scheduled for baseline = 16fd7f3fabbe663c161899d197deb66a7ec188b5 and contender = 4755e0f24411a02ad5cd839a64ca2d1a43f6df6c. 4755e0f24411a02ad5cd839a64ca2d1a43f6df6c is a master commit associated with this PR. Results will be available as each benchmark for each run completes. Conbench compare runs links: [Finished :arrow_down:0.0% :arrow_up:0.0%] ec2-t3-xlarge-us-east-2 [Failed :arrow_down:0.0% :arrow_up:0.0%] test-mac-arm [Finished :arrow_down:0.0% :arrow_up:0.0%] ursa-i9-9960x [Finished :arrow_down:0.75% :arrow_up:0.0%] ursa-thinkcentre-m75q Buildkite builds: [Finished] 4755e0f2 ec2-t3-xlarge-us-east-2 [Failed] 4755e0f2 test-mac-arm [Finished] 4755e0f2 ursa-i9-9960x [Finished] 4755e0f2 ursa-thinkcentre-m75q [Finished] 16fd7f3f ec2-t3-xlarge-us-east-2 [Failed] 16fd7f3f test-mac-arm [Finished] 16fd7f3f ursa-i9-9960x [Finished] 16fd7f3f ursa-thinkcentre-m75q Supported benchmarks: ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True test-mac-arm: Supported benchmark langs: C++, Python, R ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java