support protobuf struct type

[tscottcoombes1]

Rationale for this change

extra support for protobuf common types, converting to parquet

What changes are included in this PR?

support for protobuf struct and tests

Are these changes tested?

yes

Are there any user-facing changes?

no, just support for new type

[tscottcoombes1]

@zeroshade can I get your thoughts on this?

spark follows this pattern: https://spark.apache.org/docs/latest/sql-data-sources-protobuf.html#handling-circular-references-protobuf-fields

syntax = "proto3"
message Person {
  string name = 1;
  Person bff = 2
}

// The protobuf schema defined above, would be converted into a Spark SQL columns with the following
// structure based on `recursive.fields.max.depth` value.

0: struct<name: string, bff: null>
1: struct<name string, bff: <name: string, bff: null>>
2: struct<name string, bff: <name: string, bff: struct<name: string, bff: null>>> ...

but parquet can't do null types

my idea, is if we get to depth = x, then we drop the field? e.g. for 2

2: struct<name string, bff: <name: string, bff: struct<name: string>>>

[tscottcoombes1]

@zeroshade otherwise, as this is used for json type fields, we could convert to a json string. and not need to think about recursive depths

[zeroshade]

if the intent here is to use it for specifically JSON fields, then i would say we just use a string and utilize the Canonical JSON extension type so that it gets stored in parquet as a JSON typed field.

[zeroshade]

Looking good, just a few nit picks

[zeroshade]

can you shift these includes to be grouped with the others of the same prefix below?

[zeroshade]

same as above, please place this with the sorted imports below

[zeroshade]

@tscottcoombes1 Running pre-commit should be sufficient to fix the linting issues