Upgrade the parser to use the ProductionBreakdown, ProductionMix,
TotalConsumption, and ZoneKey classes. This should yield no functional
change. Note that this does not resolve the current issue with the
fetch_consumption function. Additionally:

- Comply with Black's 88-column default line length limit.
- Factor out duplicate code.

Refs: electricitymaps#5986, electricitymaps#6011, electricitymaps#6013

- Be more specific about the return type of the _request function.
- Import the Any type directly.
- Swap out pytz in exchange for zoneinfo.
- Use the ProductionMix.add_value method instead of a dictionary
  comprehension.

Refs: electricitymaps#5986, electricitymaps#6011, electricitymaps#6013

Swap out TotalConsumption for TotalConsumptionList, as the former is
considered an implementation detail while the latter is part of the
public API.

Refs: electricitymaps#5986, electricitymaps#6011, electricitymaps#6013

Refs: electricitymaps#5986, electricitymaps#6011, electricitymaps#6013