DerivationInfo -> PackageInfo

[roberth]

This does not yet resolve the coupling between packages and derivations, but it makes the code more consistent with the terminology, and it accentuates places where the coupling is obvious, such as

         auto drvPath = packageInfo.queryDrvPath();
         if (!drvPath)
             throw Error("'%s' is not a derivation", what());

... which isn't wrong, and in my opinion, doesn't even look wrong, because it just reflects the current logic. However, I do like that we can now start to see in the code that this coupling is perhaps a bit arbitrary.
After this rename, we can bring the DerivingPath concept into type and start to lift this limitation.

Motivation

• RFC 92 dynamic derivations
• Multi-derivation packages (ie simplify bootstrapping with separate doc derivation, without changing the in-language package interface) (we love you, staging team)
• Chip away at the derivation - package confusion.

Context

• Applies to the code doc/glossary: Define package and package attribute set #9762

Priorities and Process

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[github-actions]

Backport failed for 2.19-maintenance, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin 2.19-maintenance
git worktree add -d .worktree/backport-9786-to-2.19-maintenance origin/2.19-maintenance
cd .worktree/backport-9786-to-2.19-maintenance
git switch --create backport-9786-to-2.19-maintenance
git cherry-pick -x 65255edc9b0c2bbe8b0be50ac7b2671b50309ea8 ea6aa5ffd87b27ddd89cab541f4b98b3efcb7ea9

[roberth]

Backport conflicts with 6268a45

• which is Make profile element names stable #9656

If a backport is desired, the rename can be recreated with a case preserving find and replace on DerivationInfo, DerivationInfos and one other identifier starting with DerivationInfo.