Adds open-telemetry/opentelemetry-metrics-runtime 0.1.0 as a production
dependency so the distro automatically exports PHP runtime metrics (memory,
GC, etc.) via the native async OTLP transport.

Supporting changes required to make eager SDK initialization safe:

- PhpPartFacade::earlySetup() now also registers the distro's resource-
  attribute override and SPI detector, not only the native OTLP serializer
  and transport factory. $nativePartVersion is stored before
  registerAutoloaderForVendorDir() runs so earlySetup() can read it when
  triggered by a Composer files-autoload entry.

- New tools/build/fix_composer_autoload_order.php applies two ordering
  fixes to any vendor directory (scoped and not_scoped alike):
  1. Prepends earlySetup.php as the very first files-autoload entry so
     the distro's overrides win the race against eager instrumentation init.
  2. Reorders exporter-otlp/_register.php before sdk/_autoload.php so that
     OTLP exporter factories are registered when the SDK auto-initializer
     runs during eager init (fixes "Span exporter factory not defined for:
     otlp" on non-scoped builds).
  The two ordering fixes previously embedded in fix_scoped_composer_autoload.php
  (scoped-only) are removed from there; that script now only handles the three
  scoping-specific fixes (ClassLoader rewrite, PSR-4/classmap rewrite, hash
  rehashing).

- MockOTelCollector now accepts /v1/metrics and /v1/logs with HTTP 202 so
  the collector mock does not crash when metrics-runtime triggers a metrics
  flush on request shutdown.

- generate_composer_lock_files.sh excludes opentelemetry-metrics-runtime
  from the test lock-file variant (consistent with opentelemetry-auto-*).