feat(codegen): Remove Go-specific overrides from codegen proto

[kyleconroy]

As part of our long-term plans for additional languages, we're cleaning up the interface between sqlc and codegen plugins. This change removes the rename and overrides struct, as it had Go-specific information. In it's place is a plugin-agnostic global options block. The current Go-specific configuration looks like this:

version: "2"
overrides:
  go:
    rename:
      one: "ONE"
    overrides:
      - db_type: "text"
        go_type: "github.com/sqlc-dev/sqlc-testdata/pkg.CustomType"
      - column: "overrides.three"
        go_type:
          import: "github.com/sqlc-dev/sqlc-testdata/pkg"
          type: "CustomType"
sql:
- schema: "schema.sql"
  queries: "query.sql"
  engine: "postgresql"
  gen:
    go: 
      out: "db"
      rename:
        one: "ONE"
      overrides:
        - column: "overrides.three"
          go_type:
            import: "invalid/import"
            type: "ShouldNotSeeThis"

A two line change to use this with a theoretical Go plugin

version: "2"
plugins:
- name: go
  wasm:
    url: https://downloads.sqlc.dev/plugin/sqlc-gen-go_X.X.X.wasm
    sha256: ""
options:
  go:
    rename:
      one: "ONE"
    overrides:
      - db_type: "text"
        go_type: "github.com/sqlc-dev/sqlc-testdata/pkg.CustomType"
      - column: "overrides.three"
        go_type:
          import: "github.com/sqlc-dev/sqlc-testdata/pkg"
          type: "CustomType"
sql:
- schema: "schema.sql"
  queries: "query.sql"
  engine: "postgresql"
  codegen:
  - out: "db"
    plugin: go 
    options:
      rename:
        one: "ONE"
      overrides:
        - column: "overrides.three"
          go_type:
            import: "invalid/import"
            type: "ShouldNotSeeThis"

Supersedes #2918

[andrewmbenton]

sadly this should probably be queryset_options but not worth changing.

[andrewmbenton]

probably should have %w in here to give user some idea of what the error was