GH-36760: [Go] Adding avro ocf reader - schema converter

[loicalleyne]

Rationale for this change

First step in implementing an Avro reader.

What changes are included in this PR?

Added Avro schema to Arrow schema converter.

Are these changes tested?

yes

Are there any user-facing changes?

One exported functions:
ArrowSchemaFromAvro returns a new Arrow schema from an Avro schema JSON.
ArrowSchemaFromAvro(avroSchema []byte, includeTopLevel bool) (*arrow.Schema, error)

[github-actions]

⚠️ GitHub issue #36760 has been automatically assigned in GitHub to PR creator.

[zeroshade]

Just a few nitpick questions, otherwise this looks good to me

[zeroshade]

LGTM i hope rebasing this into the reader PR isn't gonna be a nightmare for you, haha

[zeroshade]

@loicalleyne looks like you've got some build/test failures. Other than fixing those issues, everything else looks good to me

[loicalleyne]

github.com/hamba/avro/v2 requires go 1.19 so the builds for go 1.17 and go 1.18 will always fail. How many go releases worth of backwards compatibility does arrow need to maintain?
Also, schema.Equal() has a bug which is demonstrated in schema_test.go, the string representation is identical but the schema.Equal() comparison fails for some reason.

[zeroshade]

@loicalleyne Hmmm, i didn't realize that. I think i'm fine with us bumping the minimum to go1.19 and dropping the go1.17/go1.18 builds. I'll put together a PR for that. Let's see if we can dig in and figure out the bug in the schema.Equals method.

[zeroshade]

@loicalleyne should this be dropped/closed in favor of #37115 ? It seems like this hasn't been updated or rebased

[loicalleyne]

@zeroshade it's up to you, I submitted the schema converter and the reader in separate PRs to keep the scope small.
To the best of my recollection #37115 contains the exactly the same code in schema.go and schema_test.go with the reader code in the rest of the files. Let me know if you want me to rebase one or both of them.

[zeroshade]

let's close this one and just use #37115 to track the whole thing. Please rebase that one and have a look at my comments there and close this one. It's likely easier to just keep it all in there than go back and forth between these and have you having to maintain both.