Add "typical charging speed" field for chargers

🚧 THIS IS A TICKET MIGRATED FROM UPVOTY. The original ticket and comments will be available for a limited time over at:
https://abrp.upvoty.com/b/request-a-feature/add-typical-charging-speed-field-for-chargers/
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There are many charging stations in my region (Eastern Canada) which claim to have charging speeds of 100 to 350kW but which in fact have only provided 50kW for months (according to Plugshare data at least). It would not be accurate to relabel them as 50kW because they might be fixed eventually, but ABRP's route planning isn't accurate if it assumes chargers will work at full speed. I have asked Open Charge Map to make this as a field but it's not clear if they will - meantime ABRP could fill the gap!