Support for TGE integration

[KrzysztofHajdamowicz]

Is your feature request related to a problem? Please describe.
Since 24.08.2024 dynamic electricity prices became available for residential usage in Poland.
All currently-available electricity providers use TGE (Towarowa Giełda Energii) Fixing 1 as reference point.
ENTSO-E, RCE and Nordpool are indexes that display values close to TGE, but not exactly TGE.
That's why TGE custom integration was created: https://github.com/PiotrMachowski/Home-Assistant-custom-components-TGE
This integration provides identical attributes format as ENTSO-E integration so little to no changes in your codebase.

Describe the solution you'd like
EV Smart Charging ConfigFlow suggests TGE Fixing1 sensor if present in Home Assistant instance

[KrzysztofHajdamowicz]

This Issue is addressed by PR #335

[KrzysztofHajdamowicz]

Pull Request is ready to be merged.
I would be glad if quick merge is possible as I want to popularize EV Smart Charging along Polish Citizens and TGE is only source of truth in terms of electricity price in Poland.