Add finalize() method to ConanFile

[AbrilRBS]

Changelog: Feature: Add finalize() method for local cache final adjustments of packages.
Docs: conan-io/docs#3820

We'll want to release a blogpost alongside the feature

Closes #15277
Closes #16707

[memsharded]

This is looking very good, good job :)

I am very happy to see that apparently the new cache design, architecture, folders, etc, seem to support this use case in a way that looks like one order of magnitude more doable than in Conan 1.

[czoido]

I'm still not super convinced about the name of the feature. Not that these are better but leaving some more options here:

customize()
modify()
prepare()
adjust()
mute()
tweak()

[memsharded]

mute()
tweak()

We have already considered all of them with @AbrilRBS (we spent some hours thinking about this 😅 ) except the last 2 mute() and tweak(), which I still think are not a better one than finalize() (I guess the first one would actually be mutate() or something like that, not mute()?)

[czoido]

mute()
tweak()

We have already considered all of them with @AbrilRBS (we spent some hours thinking about this 😅 ) except the last 2 mute() and tweak(), which I still think are not a better one than finalize() (I guess the first one would actually be mutate() or something like that, not mute()?)

yes, sorry, I meant mutate! 🤦

[perseoGI]

I guess it is the best name, I hope users won't mix post-hook concept with this new method.
LGTM 🚀