ARROW-14280: [Doc] R package Architectural Overview

[AlenkaF]

This PR adds an architectural overview of the R package to the New Contributor's Guide.

This work is co-authored by @thisisnic .

[github-actions[bot]]

https://issues.apache.org/jira/browse/ARROW-14280

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:warning: Ticket has not been started in JIRA, please click 'Start Progress'.

[AlenkaF]

Mind having a look at this PR @jonkeane @thisisnic? Wasn't sure if this should go to the R dev docs or in the New Contributor's Guide.

[AlenkaF]

+1 @jonkeane, thank you! Will include suggested and ping when I am done 🙏

[AlenkaF]

@jonkeane I think I have addressed all of you comments and the PR should be ready for another round of review.

[AlenkaF]

@thisisnic would be great to have your final review also 🙏

[ursabot]

Benchmark runs are scheduled for baseline = 02c671a3791d5f92d3ad0260396e2ee9c286670f and contender = 6d815a4d96aa63a732aa50e50242a99bea22c9c3. 6d815a4d96aa63a732aa50e50242a99bea22c9c3 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 [Failed :arrow_down:0.27% :arrow_up:0.0%] ursa-i9-9960x [Finished :arrow_down:0.14% :arrow_up:0.04%] ursa-thinkcentre-m75q Buildkite builds: [Finished] 6d815a4d ec2-t3-xlarge-us-east-2 [Failed] 6d815a4d test-mac-arm [Failed] 6d815a4d ursa-i9-9960x [Finished] 6d815a4d ursa-thinkcentre-m75q [Finished] 02c671a3 ec2-t3-xlarge-us-east-2 [Failed] 02c671a3 test-mac-arm [Failed] 02c671a3 ursa-i9-9960x [Finished] 02c671a3 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