[NS-72] Reorganize serveral packages, pt 1

[q10]

Summary:

• Move all metrics-related code to io.sparkcyclone.metrics package
• Move all serializer-related code over to io.sparkcyclone.data.serialization package
• Rename io.sparkcyclone.ve package to io.sparkcyclone.rdd to reflect the changes in the codebase
• Move io.sparkcyclone.ve.eval tests package to io.sparkcyclone.eval
• Remove WholeTextFileRawRDD and UserDefinedVeType, which are no longer in use
• Move all existing VE transfer-related code over to io.sparkcyclone.data.transfer
• Move all column vector and batch code from io.sparkcyclone.colvector to io.sparkcyclone.data.vector package
• Move all column vector conversions code from io.sparkcyclone.colvector to io.sparkcyclone.data.conversion package
• Move VeColVectorSource to io.sparkcyclone.data package
• Move column vector related code inside aveobench to io.sparkcyclone.data.vector package
• Consolidate all Spark plugin-related code into io.sparkcyclone.plugin package
• Update config values in scripts and documentation to reflect the plugin migration changes