use the df_hist for FetchForecast

took out fetch_data from technical analysis to its own module

technical_analysis: refined forecast plotting

technical_analysis: return only the hist data

technical_analysis: import fetch_forecast from src

technical_analysis: merge and plot forecasts

technical_analysis: smaller plot, rotated xtick labels

technical_analysis: robust figure saving path

error handling for plotting when fetching data goes wrong

enabled showing TA plots

technical analysis: better error handling, fetchperiodinweeks=12

technical_analysis: minor bug fixes, return df

introduced src.technical_analysis.py