Add ObjectStore::append

[tustvold]

Which issue does this PR close?

Part of apache/arrow-rs-object-store#181

Rationale for this change

Adds an append API to allow for appending to files where supported

What changes are included in this PR?

Are there any user-facing changes?

FYI @metesynnada @ozankabak @alamb

[tustvold]

If we're happy with this interface, I can look into implementing it for LocalFileSystem

[metesynnada]

I agree with the API design, I made a POC on synnada-ai#4. Thanks for the effort 😀

[ozankabak]

LGTM, thanks Raphael 👍

[alamb]

👍 the docstrings make a lot of sense -- thank you for spelling it out so clearly

[tustvold]

Ok - I'll get this in

I made a POC on synnada-ai#4

Looks good from a quick look, if you would like to get it polished up and raise a PR here I'll give a more in-depth review

[ursabot]

Benchmark runs are scheduled for baseline = 4f67296 and contender = 661bbad. 661bbad is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on ec2-t3-xlarge-us-east-2] ec2-t3-xlarge-us-east-2
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on test-mac-arm] test-mac-arm
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on ursa-i9-9960x] ursa-i9-9960x
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on ursa-thinkcentre-m75q] ursa-thinkcentre-m75q
Buildkite builds:
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