[grpc] Revisit the PlatformRelease#type naming (or typing)

[kittaakos]

Describe the request

The PlatformRelease#type is a repeated field, still singular and not aligned with other repeated fields, such as boards

Describe the current behavior

The API property does not follow the naming convention. It should be named as types and have a repeated string type. Or keep the name, and use a string

Arduino CLI version

0.36.0-rc.1

Operating system

N/A

Operating system version

n/a

Additional context

As far as I know, the types array will always have one item. I propose keeping the repeated string type and adjusting the property name to types.

Issue checklist

• I searched for previous requests in the issue tracker
• I verified the feature was still missing when using the nightly build
• My request contains all necessary details