add merging functionality when downloading historical data for tickers

[ldfdev]

Add functionality to merge historical data for each ticket. Data is fetched from Trading View 500 records, weekly frequency When data is fetched multiple times the existibg functionality allow the previously collected data to me merge into the mewly collected data, thus saving in csv file more than 500 records The csv file is overwritten

Also in this PR:

• organize test files into packages