Flatten request/response arguments (short-hand RIDL syntax)

[VojtechVitek]

Introduced in Peter's "v2" branch

• https://github.com/webrpc/webrpc/tree/schema-v2
• v0.8 with schema updates #134
• schema v2, aka webrpc-gen v0.8.0 #123

struct FlattenRequest
  - name: string
    + go.tag.db = name
  - amount?: Balance
    + go.tag.db = amount

struct FlattenResponse
  - id: uint64
    + go.field.name = ID
  - count: uint64
    + json = counter

service Another
  - Flatten(FlattenRequest) => (FlattenResponse)

[VojtechVitek]

#134 (review)

[pkieltyka]

btw, I recall this did work in the schema version I worked on some months ago? it's a nice feature to clean up the rpc interface. Did we ever get to support this in the latest versions of webrpc?

[pkieltyka]

completed in #229