Preliminary Checks

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Is your feature request related to a problem? Please describe

We chart many pairs at once with watchOHLCV (and watchTrades where an exchange streams no candles), and call unWatchOHLCV / unWatchTrades when a chart closes. On the exchanges below there is no unsubscribe, so the exchange keeps streaming every pair that was ever watched on that connection, and the client keeps parsing it into its caches, until the whole client is closed.

Checked on master (844df9e), ts/src/pro/*.ts:

Side note: bitget implements both unWatchOHLCV and unWatchTrades, but its has doesn't declare them, so code that checks has before calling them never unsubscribes there.

Describe the solution you'd like

unWatchOHLCV and unWatchTrades on these exchanges (each one's own unsubscribe message), as binance, okx, bybit, kucoin, mexc, htx, bingx and bitget have, and bitget's has flags set.

Describe alternatives you've considered

Closing the exchange's whole client once nothing on it is watched, which is what we do for now. It frees the connection, but while any chart on that exchange stays open, the pairs no longer shown keep streaming. We can send pull requests for some of these exchanges if that helps.