[vcpkg] Enable kea and freexl drivers for GDAL

[m-kuhn]

Because more drivers, more pleasure

[github-actions]

🧮 Vcpkg update report

Added packages:
🍓 kealib: 1.6.0 (Features: )

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[troopa81]

Glad to see this! I was hesitating to propose this because I was not sure how works the default-feature/recommended-feature override here and there

Btw, Is this normal ?

So far, QGIS was not able to open Geopackage because sqlite was missing because of this line

[m-kuhn]

Mixed bag of questions:

1. default-features were already enabled so far whenever built with bindings, because in the bindings dependency, default-features was not deactivated. This is not expected and actually the change that we want here.
2. The decision what's a default feature for gdal is not taken in here, this is mostly a copy of the upstream gdal port with some adjustments for python. Let's not dive into technicalities how it's implemented.
3. I would like to get rid of our gdal overlay and replace it with a gdal-python port which only builds python bindings on top of an existing gdal installation. Similar to how gdal allows to build standalone plugins for some formats. I am not 100% sure this will work but it would ease our maintenance effort.

[troopa81]

OK, I understand it better, thanks 👍

[rouault]

Because more drivers, more pleasure

I question a bit that statement, but this is apparently a not so-popular opinion in the community ;-) As white doesn't exist without black, someone has to hate them, so others can have a chance to love them. That said, my cruisade against useless write side of drivers would be well justified when I see the quite impractical UI in QGIS when you have to select the output driver when exporting a raster layer among a dropdown lis of > 50+ candidates that doesn't fit into the screen height, with a lot of them being super obscure, and that's an understatement.

[m-kuhn]

@rouault I agree that if one has to select from a list, more is not always better. But I also think in such a case there are other options like "hide unpopular drivers by default" which sits somewhere between black and white.

This PR was triggered by #60039 (comment) which mentions kea support which in turn made me think that it's probably a thing for some users (on the other hand, this might also be a purely technically motivated statement, I don't know).
freexl is actually almost a no-op, as the library itself is already bundled and just not enabled inside GDAL.

[rouault]

This PR was triggered

no problem. I wasn't questioning the soundness of this PR. KEA is probably in the slightly obscure category, that said that driver has a true originality: it was designed to be a 100% match with the GDAL raster model.

[m-kuhn]

that said that driver has a true originality:

To be kept for a fun fact at an appropriate place and time