Implement Debug for all types that work with QDebug

[jnbooth]

This PR adds Debug implementations to all types that a QDebug data stream accepts.

Note: Some types incorrectly used QDebug output to implement Display instead of Debug. This PR does not remove those implementations because that would be a breaking change, but they probably should be removed for the next major release.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (e84662a) to head (bb6f2e5).
Report is 1 commits behind head on main.

Additional details and impacted files

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##              main     #1162   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           71        71           
  Lines        11967     11967           
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  Hits         11967     11967           

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[LeonMatthesKDAB]

Hi @jnbooth, thank you for this contribution!
It's great to see you're using CXX-Qt actively and I'm very happy to see the improvements that come out of it 😃

This PR mostly looks good. I believe it can be simplified a little bit more, as the toQString function should actually not be necessary anymore, and there are a few nitpicks to take care of.

Then we should be able to merge this 🥳

[LeonMatthesKDAB]

Is there a reason why this isn't wrapped as a member function?

If not, please replace it with a member function in CXX, then you can also remove the added code in the C++ header and source :)
e.g.:

        fn qtimezoneDisplayName(
            self: &QTimeZone,
            time_type: QTimeZoneTimeType,
            name_type: QTimeZoneNameType,
        ) -> QString;

[LeonMatthesKDAB]

I appreciate the effort here to also allow upcasting the QPolygon to it's base class QList<QPoint>.

Note that we will replace this implementation with the generalized version that @BenFordTytherington is working one once it lands:
#1159
For now we can keep it as it should be compatible API-wise

[LeonMatthesKDAB]

There is already a to_string function on QAnyStringView (see line 34) which you can use.

[LeonMatthesKDAB]

This template should no longer be necessary.
If toString() is already a member function, we don't need to create a free function toQString, but can just access it directly via CXX:
i.e.:

// Maybe with #[doc(hidden)], depending on the situation
#[rust_name="to_qstring"]
fn toQString(self: &T);

Please remove this function and replace the existing references with direct member access.

[jnbooth]

The idea of this template is to allow types to have more flexibility in how they define to_qstring(). Some types have extra parameters for toString. For others, we might not want to have a to_qstring method at all (rather than relying on #[doc(hidden)]. Or we might decide not to have methods like that in general and use From<&Type> for QString, which is more idiomatic. So by using this template, types aren't "locked in" to a particular implementation; we can keep the Display logic separate from everything else.

That said, I of course defer to you. What should be the rubric for whether or not to use #[doc(hidden)]?