[ondrejmirtes]

Continues #6902. --fix now fixes two errors about ignoreErrors entries in config files:

• ignore.unmatched removes the entry. When it matched through a list like messages or identifiers that has other items, only that item is removed.
• ignore.count lowers the count when the error occurred fewer times than the entry says. A count lower than the occurrences is not fixed, it would ignore more errors - that is what --generate-baseline is for.

Where the entry is looked for

• The whole config cascade (allConfigFiles), except files of installed Composer packages. The check moved from ResultCacheManager to PackageDependencyResolver::isFileOfInstalledPackage(); packages from path repositories are still treated as the project's own code.
• Only PHP config files, like PHP baselines, are fixed so far. NEON is left for later.
• An entry is not fixed when it is unclear which one to change, like a count merged from duplicate entries or from an entry in a NEON file.

Performance
The first version used the format-preserving printer for every fix. On a WordPress level 10 baseline (31k entries, 186k lines) that took 4.4 s per error: cloning the AST and printing the whole file. Now the file is parsed once, a fix edits the source range of the node, and its diff covers only the changed lines, which is all Patcher reads. With 1,863 broken entries in that baseline, every fix takes under 1 ms and --fix finished in 28 s; the fixed baseline equals the original minus the broken entries.

The parse is lazy, but it happens on every run that reports one of these errors: about 1.5 s for the 7 MB WordPress baseline.

Removing the last items of a list
Removing an item rewrites the whole list, so removals of two items of one list conflict and go in separate rounds. Otherwise all items could be removed in one round, leaving an invalid 'messages' => [].

Tests: IgnoreErrorsConfigFixerTest applies the diffs through Patcher, and a new e2e/fix-baseline test checks the fixed baseline file, that entries in NEON and in vendor/ stay, and that --fix --generate-baseline is rejected.