Migrate from `arrow` (`apache/arrow-rs`) to `arrow2` (unofficial, safer)

[teymour-aldridge]

🌟 What is the purpose of this PR?

This migrates the engine from arrow (https://github.com/apache/arrow-rs) to arrow2 (https://github.com/jorgecarleitao/arrow2).

🔗 Related links

• Asana task (internal)

🔍 What does this change?

• Removes arrow and replaces it with arrow2. In many cases, the code is now a lot safer than it used to be.

⚠️ Known issues

• warning: it compiles but in some cases I just took a guess as to what the correct implementation was (and will need to test this)
• slower expected simulation run executions

🛡 What tests cover this?

• The test suite (let us hope)

[vilkinsons]

Would love to see performance benchmarks between the two (although accept we're committed to this now anyway for reasons extensively internally documented).

[vilkinsons]

@teymour-aldridge I've tagged Tim and Alfie in as reviewers now this has been marked ready. If you'd prefer they hold, please Slack.