SnapStart integration enhancement

[cescoffier]

• Write documentation
• Use SnapStart instead of CRaC to avoid the confusion

[gsmet]

I added a few suggestions and comments.

[geoand]

Very good idea to break Crac and Snapstart up in the code.

[loicmathieu]

SnapStart is only for Amazon Lambda right ?
Maybe it should be moved to the Amazon Lambda extension.

My understanding is that CRaC support was removed now, it's a little shame as it was promising but I understand that such early tech is not yet supported.

[quarkus-bot]

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[gsmet]

@loicmathieu this PR doesn't remove any CRaC feature. CracConfig was introduced very recently specifically for SnapStart. If at some point, it makes sense to generalize, we can still tweak things.

[cescoffier]

@loicmathieu CracConfig was introduced very recently as a placeholder for SnapStart - before we can use that name in public.

It does not remove the CRaC support, it just makes things less confusing, as if you would have used the SnapStart feature with another CRaC impl.... bad things would have happened.

[loicmathieu]

@gsmet @cescoffier I see now that CRaC support is in RunnerClassLoader and this has nothing to do with SnapStart. Thanks for the clarifications.