Verify the MessageFormat package in a consumer, the Native AOT gate and CI #40

Feature 09 of the 11 features of ResXLocalization 2.0.0, parent issue #29. "Feature NN" in this
issue means an entry of the numbered feature list in the parent issue.

Why

Every package receives consumption checks from its packed .nupkg, restored through a
PackageReference alone. Core, Avalonia and MessageFormat also receive Native AOT publishing with zero
IL diagnostics and checks of the native binary's output; WPF has no Native AOT support. The new
ResXLocalization.MessageFormat package still needs to be added to these checks.

What changes

• New package-only consumer tests/package-consumption/MessageFormatConsumer (net8.0, net10.0):
  ICU plurals in compiled XAML and in code, in English and German.
• scripts/verify-package-aot.ps1 publishes and runs both the Avalonia and the MessageFormat consumer.
• scripts/pre-release-gate.ps1 and CI run the new consumer; the publish job expects four packages.
• Native AOT guide: the package's cost, its AOT safety, and what InvariantGlobalization=true means
  for a localized application.

Acceptance criteria

• Both consumers publish as Native AOT with zero IL2xxx/IL3xxx diagnostics, and their binaries pass,
  on net8.0 and net10.0.
• The release gate and CI run MessageFormatConsumer.

Details

• Depends on: Register the generated resource managers and reject missing resources #35 (04), Take format arguments on the binding instead of LocalizeArgs #36 (05), Add the opt-in ResXLocalization.MessageFormat package for ICU plural and select #39 (08).