Add export_conandata_patches utility

[MartinDelille]

Changelog: Feature: Add export_conandata_patches tool.
Docs: conan-io/docs#2720

Closes: #11770
Closes: #11923

This issue has no test because I didn't managed to make it work but you can see this as a quick proposal before going further in the implementation.

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^{Note: By default this PR will skip the slower tests and will use a limited set of python versions. Check here how to increase the testing level by writing some tags in the current PR body text.}

[MartinDelille]

@jgsogo I'll be happy to have your feedback on this feature that would replace this two lines by a simpler export_conandata_patches(self). Feel free to ping anyone who would be interested in this.

[jgsogo]

I suggested it too on my side... just to discover that @SpaceIm already suggested some days ago. IIRC it is assigned to 1.53

[jgsogo]

Anyway, I don't know if there's already a PR for it. When I'm back on my computer I'll have a look to the implementation

[SpaceIm]

related issue: #11770

[memsharded]

This would need some integration tests

[memsharded]

We would like this to be in 1.52 soon, so I have contributed a review, including completing the test and more error checking.

[MartinDelille]

Thanks!

[jcar87]

LGTM!