Upgrade to grpc-gateway V2

[amaury1093]

Summary

Upgrade to grpc-gateway V2

Problem Definition

From the author:

The grpc-gateway v1 is in maintenance mode, you are encouraged to migrate to v2. Check out our v2 migration guide.

Proposal

Follow the migration guide.

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[amaury1093]

Note that grpc-gateway in v2 defaults to camelCase, which is also the default ProtoJSON spec case.

We should make a decision whether to switch to camelCase everywhere (con: huge client breaking change) or stick with camel_case (con: not following SPEC).

My preference is to eventually switch to camelCase, so that we don't have inconsistencies anymore, see e.g. (totalWeight vs total_weight in the docs).

(credits to @haveanicedavid for flagging this)

[aaronc]

I believe this will only be possible once we migrate away from gogo to google.golang.org/protobuf.

[alexanderbez]

I personally hate seeing camel-case in JSON, but this is what Google recommends so 🤷

[aaronc]

I personally hate seeing camel-case in JSON, but this is what Google recommends so 🤷

I really would prefer to stick to the proto names for fields in JSON. It is configurable and I think we should take advantage of that.

[julienrbrt]

Is that something we should do while adding it to server/v2?
ref: #20798

cc @tac0turtle & @testinginprod

[julienrbrt]

The support of gRPC gateway is v2 will be done differently as we want to remove the gRPC registration requirement from modules.
This is being tracked by #20798