Improve logging in getNextRandomBlockSize()

[fpahlke]

Add comprehensive logging information at each block size randomization step, see TODO below:

getNextRandomBlockSize = function() {
    if (is.null(blockSizes) || length(blockSizes) == 0) {
        stop("No block sizes are defined")
    }

    if (length(blockSizes) == 1) {
        return(blockSizes[[1]])
    }

    if (fixedBlockDesignEnabled) {
        randomIndex <- fixedBlockIndex
    } else {
        if (is.null(blockSizeRandomizer)) {
            stop("'blockSizeRandomizer' is not initialized")
        }
        
        randomIndex <- blockSizeRandomizer$nextInt(length(blockSizes))
        message("Get next random block size (index = ", randomIndex, ")")
    }

    blockSize <- blockSizes[[randomIndex]]

    # TODO logging
    # Map<String, Object> rndLoggerValues = new HashMap<String, Object>()
    # rndLoggerValues.put("blockSize", "new random block size: " + blockSize + " (random index: " + randomIndex + ")")
    # logger.info("Random configuration set: " + rndLoggerValues)

    return(blockSize)
}