set up org.fdroid and io.gitlab.fdroid on Maven Central OSSRH

With the FFDW-DVD work, we'll be creating libraries from core parts of fdroidclient. So to have a canonical place to publish this, we need an official group on Maven Central OSSRH. I filed the issue on their JIRA and created the https://gitlab.com/fdroid/OSSRH-78462 group for verification. @CiaranG will have to add the TXT record to verify the fdroid.org domain name. Note: this is without the dash, since it matches https://gitlab.com/fdroid and the fdroid command. We could probably also use org.f-droid if anyone has a strong opinion.

@grote and @eighthave are currently requested to have access to publish there.

• https://issues.sonatype.org/browse/OSSRH-78462
• https://issues.sonatype.org/browse/OSSRH-78463

• https://central.sonatype.org/faq/verify-ownership/
• add GitLab project https://gitlab.com/fdroid/OSSRH-78463
• https://central.sonatype.org/faq/how-to-set-txt-record/
• https://issues.sonatype.org/browse/OSSRH-80375 @grote needs io.gitlab.fdroid access
• https://issues.sonatype.org/browse/OSSRH-80374 @grote needs org.fdroid access