fix: outputSchema=true when onlyTypes=true (#1039)

This PR aims to fix a conflict that is created between two options that
results in code that fails to compile. Please note that this is not an
attempt to fix the underlying problem, which I have explained in a TODO
comment in the code for posterity. I also created new tests to capture
any regressions.

---------

Co-authored-by: semantic-release-bot <semantic-release-bot@martynus.net>

integration/options-types-only/options-test.ts

@@ -0,0 +1,11 @@
+import { protoMetadata } from "./options";
+
+describe("options", () => {
+  it("compiles", () => {
+    expect(protoMetadata).not.toBeUndefined();
+  });
+
+  it("has the right options", () => {
+    expect(protoMetadata.options?.messages?.["MyMessage"]?.options?.["my_message_option"]).toBe(1234);
+  });
+});

integration/options-types-only/options.proto

@@ -0,0 +1,75 @@
+syntax = "proto3";
+
+import "google/protobuf/descriptor.proto";
+import "something/something.proto";
+
+extend google.protobuf.FileOptions {
+  optional string my_file_option = 50000;
+}
+
+extend google.protobuf.MessageOptions {
+  optional int32 my_message_option = 50001;
+}
+
+extend google.protobuf.FieldOptions {
+  optional float my_field_option = 50002;
+}
+
+extend google.protobuf.OneofOptions {
+  optional int64 my_oneof_option = 50003;
+}
+
+extend google.protobuf.EnumOptions {
+  optional bool my_enum_option = 50004;
+}
+
+extend google.protobuf.EnumValueOptions {
+  optional uint32 my_enum_value_option = 50005;
+}
+
+extend google.protobuf.ServiceOptions {
+  optional MyEnum my_service_option = 50006;
+}
+
+extend google.protobuf.MethodOptions {
+  optional MyMessage my_method_option = 50007;
+}
+
+option (my_file_option) = "Hello world!";
+
+message MyMessage {
+  option (my_message_option) = 1234;
+
+  optional int32 foo = 1 [(my_field_option) = 4.5];
+  optional int32 foo_2 = 2 [(something.something) = {
+    hello: "world";
+    foo: [123, 345];
+  }];
+  optional string bar = 3;
+  oneof qux {
+    option (my_oneof_option) = 42;
+
+    string quux = 4;
+  }
+}
+
+enum MyEnum {
+  option (my_enum_option) = true;
+
+  FOO = 0 [(my_enum_value_option) = 321];
+  BAR = 1;
+}
+
+message RequestType {}
+message ResponseType {}
+
+service MyService {
+  option (my_service_option) = FOO;
+
+  rpc MyMethod(RequestType) returns(ResponseType) {
+    option (my_method_option).foo = 150;
+    option (my_method_option).foo_2 = 150;
+    option (my_method_option).bar = "Some string";
+    option (my_method_option).quux = "Some string";
+  }
+}