btcli4j: archive plugin

[daywalker90]

@clightning4j i want to archive this plugin because it seems unmaintained and there seem to be issues suggesting that it doesn't work for current CLN versions anymore, like clightning4j/btcli4j#79. There have been no commits in 2 years and there are no tests to show if this plugin still works.

I couldn't build the plugin myself to confirm this:

FAILURE: Build failed with an exception.

* What went wrong:
Could not determine the dependencies of task ':createRunnableScript'.
> Could not create task ':fatJar'.
   > Could not resolve all files for configuration ':runtimeClasspath'.
      > Could not find io.github.clightning4j:jrpclightning:0.2.5-SNAPSHOT.
        Searched in the following locations:
          - https://jcenter.bintray.com/io/github/clightning4j/jrpclightning/0.2.5-SNAPSHOT/maven-metadata.xml
          - https://jcenter.bintray.com/io/github/clightning4j/jrpclightning/0.2.5-SNAPSHOT/jrpclightning-0.2.5-SNAPSHOT.pom
          - https://repo.maven.apache.org/maven2/io/github/clightning4j/jrpclightning/0.2.5-SNAPSHOT/maven-metadata.xml
          - https://repo.maven.apache.org/maven2/io/github/clightning4j/jrpclightning/0.2.5-SNAPSHOT/jrpclightning-0.2.5-SNAPSHOT.pom
          - https://oss.sonatype.org/content/repositories/snapshots/io/github/clightning4j/jrpclightning/0.2.5-SNAPSHOT/maven-metadata.xml
          - https://oss.sonatype.org/content/repositories/snapshots/io/github/clightning4j/jrpclightning/0.2.5-SNAPSHOT/jrpclightning-0.2.5-SNAPSHOT.pom
        Required by:
            project :
      > Could not find io.github.clightning4j:lite-bitcoin-rpc:0.0.1-rc2-SNAPSHOT.
        Searched in the following locations:
          - https://jcenter.bintray.com/io/github/clightning4j/lite-bitcoin-rpc/0.0.1-rc2-SNAPSHOT/maven-metadata.xml
          - https://jcenter.bintray.com/io/github/clightning4j/lite-bitcoin-rpc/0.0.1-rc2-SNAPSHOT/lite-bitcoin-rpc-0.0.1-rc2-SNAPSHOT.pom
          - https://repo.maven.apache.org/maven2/io/github/clightning4j/lite-bitcoin-rpc/0.0.1-rc2-SNAPSHOT/maven-metadata.xml
          - https://repo.maven.apache.org/maven2/io/github/clightning4j/lite-bitcoin-rpc/0.0.1-rc2-SNAPSHOT/lite-bitcoin-rpc-0.0.1-rc2-SNAPSHOT.pom
          - https://oss.sonatype.org/content/repositories/snapshots/io/github/clightning4j/lite-bitcoin-rpc/0.0.1-rc2-SNAPSHOT/maven-metadata.xml
          - https://oss.sonatype.org/content/repositories/snapshots/io/github/clightning4j/lite-bitcoin-rpc/0.0.1-rc2-SNAPSHOT/lite-bitcoin-rpc-0.0.1-rc2-SNAPSHOT.pom
        Required by:
            project :

If you can confirm that the plugin still works or that you intend to maintain it, i will close this PR.