presets: Allow extending/overriding of existing presets

Suppose I have some common and msvs configurePresets in CMakePresets.json. Their content is irrelevant (msvs inherits common) but they have some reasonable defaults with all the build and test presets written around them. Now I'm a user of that project and I want to change some details. For example, the project defaults to MSVS 2019 and I use 2022, I also happen to know where Boost on my system located etc. So I'd want to do the following in my CMakeUserPresets.json:

{
    "version": 3,
    "configurePresets": [
        {
            "name": "common",
            "cacheVariables": {
                "Boost_DIR": "Path/To/Boost/Config"
            },
            "vendor": {
                "jetbrains.com/clion": {
                    "toolchain": "Visual Studio"
                }
            }
        },
        {
            "name": "msvs",
            "generator": "Visual Studio 17 2022"
        }
    ]
}

And that's it, no additional build or test presets, no nothing. So I then go to the console, type cmake --preset msvs and it correctly finds Boost and generate me a MSVS 2022 solution file.

Some might say that it is feasible with inheritance and it is but even for such a simple configuration it requires too much typing. With more presets it would be simply unapproachable. Besides I don't want to generate new presets, I use the same msvs preset that everyone else, just customized it a little bit to adjust it to my local needs. And in my opinion CMakeUserPresets.json is exactly the place for such customizations.

Note that I'm not proposing any particular syntax, just a general idea. Maybe the extending preset should have the "extending" attribute, maybe it should have something like: "extends": ["one", "two", "three"] or maybe leave it as is and just merge all the presets with the same name with "later setting wins" as always.