Converted market times sensor to ISO Date Time format & added AUD Currency

[cabberley]

This update provides 2 enhancements to your code

1. Added AUD currency code so currency attribute will now correctly identify and display Australian stocks currencies. Previously it was displaying unknown.
2. The regularMarketTime & postMarketTime attributes were being displayed in Epoch, added code to convert these to a full DateTime with TimeZone aware value.

[iprak]

You would need to adjust test_sensor.py as well. You can add a check like done for DATA_REGULAR_MARKET_PRICE or some other way to confirm the null return value for the 2 atributes.

    # All numeric values besides DATA_REGULAR_MARKET_PRICE should be 0
    for data_group in NUMERIC_DATA_GROUPS.values():
        for value in data_group:
            key = value[0]
            if (key != DATA_REGULAR_MARKET_PRICE) and (key != DATA_DIVIDEND_DATE):   # noqa: PLR1714
                assert attributes[key] == 0

[cabberley]

@iprak Thanks for the feedback. I have refactored the timestamp conversion and consolidated the two into a single one. The refactored also facilitates that Dividend Date is just a date no time. Market times, the date and time are relevant.

Also added the tests as requested.

[iprak]

The combined function now returns 0 for missing (None) input. We should keep previous behavior of None. In cases where data might be missing, the result None can be treated differently than 0.

[iprak]

Sorry but now a few different tests are failing. The tests are in test_sensor.py (test_parse_dividend_date) which is failing because it is using the older function.

[cabberley]

reverted return value to be date_timestamp value to support the None and 0 use case. If 0 gets through and converted it would result in a 1970 date. Rewrote the tests for the renamed function and added the extra testing to it to reflect the changes in the function. **Sorry been a little while since I have done all of this. Hopefully this fixes it all up.