Improve concurrent requests handling

Use proper locking to prevent concurrent asyncio tasks overlaps.

Adjust the settings API

Rename set_work_mode to set_operation_mode.
Rename read_settings to read_setting (+ same for write).
Add read settings methods

Add support for MS inverters

Add proper support for MS inverters, exposing also 3rd PV string values.
Adjust units of apparent and reactive power values.
Remove invalid ES e_total_* sensors.

Decode -0.1 energy values as None

Some inverters report 0xFFFFFFFF as no value in energy sensor (e_total/e_day).
Interpret them as None value to avoid odd drops in otherwise strictly rising function.

Report consecutive failures in RequestFailedException

Report consecutive failures in RequestFailedException

Change formulas for the house_consumption sensors to their most reliable variants.
Expose diag_status sensor as both code and label.

Fix ES house_consumption

Fix ES house_consumption

Use constant for UDP port

Use a constant variable for the UDP port

Fix power factor and house_consumption

Fix power factor scale, so the values are in proper -1 to 1 range.
Fix house_consumption for ES inverter, backup-up line consumption was not included.

Add diag status bits decoding

Decode diagnostic status bits to human readable messages for ET and ES based inverters.

Add support for ET/EH/ES/EM/DT/D-NS/BP inverter families

Major overhaul of the source code and API incorporating code from the HomeAssistant plugin.
The library now supports broad range of GoodWe inverters and lots of new sensors and settings.
The old API based on GoodWeInverter and GoodWeXSProcessor is still there for backwards compatibility (for XS inverters only),
but the new API based on Inverter class is the preferred one.