return the default style first in the list

[Gustry]

Description

iface.activeLayer().listStylesInDatabase()
(3, ['60', '122', '120', '129', '128', ..............

With this fix, I know that 60 is the default style, 122 and 120 are other related styles, 129, 128 etc are non related styles.

It's the only way in the API to know the default style.

Checklist

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[nyalldawson]

Looks good! Can you update the style test in test_provider_postgres to match?

[Gustry]

@nyalldawson I just added some tests.

While I was writing the test, I realized that I always have a default style in my DB for my layers. So this patch works only when we are sure that there is a default style. I can add a function later to know if there is a default style. Is-it fine like this @nyalldawson ?

BTW, are PG tests running on travis? or only locally?

[m-kuhn]

BTW, are PG tests running on travis? or only locally?

On travis also

[Gustry]

OK. Let me know if it's OK for 3.2 or 3.4.

I will have some time in July about styles.

[nyalldawson]

While I was writing the test, I realized that I always have a default style in my DB for my layers. So this patch works only when we are sure that there is a default style. I can add a function later to know if there is a default style. Is-it fine like this @nyalldawson ?

In that case, do you think it's better to just add a new function to retrieve the default style? (returning an empty string if none is set)

[Gustry]

Yes, I'm planning to add this function as soon as the feature freeze is finished.
I would still need this PR anyway I think. If I implement only the get defaultStyle, I would need to compare each XML one per one to know which one is the default in the result from iface.activeLayer().listStylesInDatabase().

[Gustry]

Gentle ping to have one PR less in the pending queue for 3.2?
I would still need this PR anyway for my side.

[nyalldawson]

Sure, let's merge.

[Gustry]

Thanks