[programgen] Spot and qualify duplicate identifiers

[lunaris]

The l2-map-keys conformance test fails because two packages which provide a Resource class are imported, and the names are not qualified appropriately in order to avoid ambiguity:

package generated_program;

import com.pulumi.Context;
import com.pulumi.Pulumi;
import com.pulumi.core.Output;
import com.pulumi.primitive.Resource;
import com.pulumi.primitive.ResourceArgs;
import com.pulumi.primitiveref.Resource;
import com.pulumi.primitiveref.ResourceArgs;
import com.pulumi.primitiveref.inputs.DataArgs;
import com.pulumi.refref.Resource;
import com.pulumi.refref.ResourceArgs;
import com.pulumi.refref.inputs.DataArgs;
import com.pulumi.refref.inputs.InnerDataArgs;
import com.pulumi.plain.Resource;
import com.pulumi.plain.ResourceArgs;
import com.pulumi.plain.inputs.DataArgs;
import com.pulumi.plain.inputs.InnerDataArgs;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.io.File;
import java.nio.file.Files;
import java.nio.file.Paths;

public class App {
    public static void main(String[] args) {
        Pulumi.run(App::stack);
    }

    public static void stack(Context ctx) {
        var prim = new Resource("prim", ResourceArgs.builder()
            .boolean_(false)
            .float_(2.17)
            .integer(-12)
            .string("Goodbye")
            .numberArray(            
                0,
                1)
            .booleanMap(Map.ofEntries(
                Map.entry("my key", false),
                Map.entry("my.key", true),
                Map.entry("my-key", false),
                Map.entry("my_key", true),
                Map.entry("MY_KEY", false),
                Map.entry("myKey", true)
            ))
            .build());

...

Here, new Resource could refer to any of com.pulumi.primitive.Resource, com.pulumi.primitiveref.Resource, com.pulumi.plain.Resource, or com.pulumi.refref.Resource.

[Zaid-Ajaj]

Duplicate of #1558