Add support for creating charts

[dborovcanin]

Add support for creating charts

[ianmuchyri]

• Based on the research in this issue #81, and this PoC #89, You should create configurable chart templates.

• The chart templates will be added to the widgets we will have created in the layout.

• All the charts should be able to use the SENML data format used in Magistrala

• Configuration of the data being used by the chart widget:
  1. Source (channel, and publisher)
  2. Fetch interval (last 1minute, 1hr, 1day e.t.c.)
  3. Data aggregation to be used (min, max, average, sum, count, none)
  4. Grouping interval (based on the fetch interval)
  5. User to choose which data to display (ie. realtime, or historical)
  6. Data name (key), label, color, units, decimals
  7. titles, axis naming, e.t.c