Supply dummy ossrh credentials when none available

[robobario]

This enables commands like ./gradlew build to work without supplying credentials in a gradle.properties file.

Now with no gradle.properties file in the project dir or your ~/.gradle dir you can run commands like ./gradlew build and ./gradlew test

[roby@roby pcollections]$ ./gradlew clean test

> Configure project :
Project : => 'org.pcollections' Java module

> Task :compileTestJava
warning: [options] module name in --add-exports option not found: org.junit.jupiter.engine
1 warning

BUILD SUCCESSFUL in 5s

And to check it's picking up the property from the required locations:

1. no gradle.properties file

./gradlew publish -xsignMavenJavaPublication --debug | grep dummy
2023-11-08T12:00:44.248+1300 [DEBUG] [org.gradle.internal.resource.transport.http.HttpClientConfigurer] Using Credentials [username: dummy] and NTLM Credentials [user: dummy, domain: , workstation: ROBY] for authenticating against 'oss.sonatype.org:-1' using NTLM
2023-11-08T12:00:44.248+1300 [DEBUG] [org.gradle.internal.resource.transport.http.HttpClientConfigurer] Using Credentials [username: dummy] for authenticating against 'oss.sonatype.org:-1' using null

2. with gradle.properties containing name/pass == "real" in the project dir

./gradlew publish -xsignMavenJavaPublication --debug | grep real
2023-11-08T12:01:28.727+1300 [DEBUG] [org.gradle.internal.resource.transport.http.HttpClientConfigurer] Using Credentials [username: real] and NTLM Credentials [user: real, domain: , workstation: ROBY] for authenticating against 'oss.sonatype.org:-1' using NTLM
2023-11-08T12:01:28.727+1300 [DEBUG] [org.gradle.internal.resource.transport.http.HttpClientConfigurer] Using Credentials [username: real] for authenticating against 'oss.sonatype.org:-1' using null

3. with gradle.properties containing name/pass == "real" in ~/.gradle

./gradlew publish -xsignMavenJavaPublication --debug | grep real
2023-11-08T12:02:12.949+1300 [DEBUG] [org.gradle.internal.resource.transport.http.HttpClientConfigurer] Using Credentials [username: real] and NTLM Credentials [user: real, domain: , workstation: ROBY] for authenticating against 'oss.sonatype.org:-1' using NTLM
2023-11-08T12:02:12.949+1300 [DEBUG] [org.gradle.internal.resource.transport.http.HttpClientConfigurer] Using Credentials [username: real] for authenticating against 'oss.sonatype.org:-1' using null

Why:
The context is we are rebuilding from source and publishing to a custom maven repository and currently have to inject a gradle.properties file to make the gradle build run.

Closes #112

[hrldcpr]

So fast, thanks a lot!