use fully qualified name when generating messages

[nbaztec]

Fixes #47

For the following protobuf where the oneof field had the same name as message, the companion object definition would shadow the oneof class instead of the message class. This patch fixes it by fully qualifying the message class name.

Input:

syntax = "proto3";
package foobar;

message Value {
    oneof value {
        int32 int_val = 1;
        string str_val = 2;
    }
}

Before:

package foobar

data class Value(
        val value: Value<*>? = null,
        override val unknownFields: Map<Int, pbandk.UnknownField> = emptyMap()
) : pbandk.Message {
       sealed class Value<V>(value: V) : pbandk.Message.OneOf<V>(value) {
              ...
       }
       ...
       companion object : pbandk.Message.Companion<Value> {
              ...
       }
       ...
}

After:

package foobar

data class Value(
        val value: Value<*>? = null,
        override val unknownFields: Map<Int, pbandk.UnknownField> = emptyMap()
) : pbandk.Message {
       sealed class Value<V>(value: V) : pbandk.Message.OneOf<V>(value) {
              ...
       }
       ...
       companion object : pbandk.Message.Companion<foobar.Value> {
              ...
       }
       ...
}

[garyp]

Thank you for fixing this! Sorry for the delay in reviewing your change.

[garyp]

👍