feat(arrow/_examples): enhance library examples

[kris-gaudel]

Rationale for this change

Enhancing the library examples

What changes are included in this PR?

3 new examples on how to use the arrow-go library:

• Reading from a CSV file
• Type conversions
• Managing performance

Are these changes tested?

Not applicable

Are there any user-facing changes?

No, just enhancing examples

[zeroshade]

Instead of using the _examples folder, could we instead make these testable examples in the appropriate locations so they show up in the docs directly next to the relevant code?

[zeroshade]

Some files are missing the Apache license header, adding that should fix the CI

[zeroshade]

hey i'm super sorry this is taking so long! I've been traveling for a conference. I'll review this and hopefully merge it today

[zeroshade]

These are great examples! Thanks so much for this

[zeroshade]

@kris-gaudel looks like you need to update the tinygo test script because you renamed/moved the helloworld/main.go file 😄 that's probably the last thing we need before we can merge this

[kris-gaudel]

It looks like there is a memory leak in one of the tests, should I fix it in this PR or make a separate one?

[zeroshade]

That's a transient leak that I haven't been able to track down myself. If you're able to track it down and fix it, that would be amazing! It can definitely be a separate PR and doesn't need to be dealt with in this one.