Initial config changes for 2.x versions:
* update to php 8.2 minimum
* gitsplit 2.x
* skip rector ReadOnlyClassRector

Limit the default detectors from everything to:
- sdk
- sdk_provided
- env

This is controlled by a new detector key, OTEL_PHP_DETECTORS=default (which is
the default if no value is provided). The previous behaviour can be restored
by explicitly setting OTEL_PHP_DETECTORS=all.

open-telemetry/opentelemetry-specification#3907 implements some new
requirements for logging:
- ReadWriteLogRecord can mutate (eg by processors)
- mutated ReadWriteLogRecord can be seen by later processors

This is a breaking change because LogRecordProcessorInterface onEmit param changes to by-reference

To resolve our long-standing race conditions stemming from using composer's autoload->files
to registry SDK components at runtime, this changes things so that:
- components are registerd in various _register.php files, and SPI is used to remove those files from autoload->files
- the SDK Registry is removed, replaced by an internal service loader which interacts with SPI similarly to how the Registry did

add a test to demonstrate that mutations are still seen by later processors without by-reference

* added to spec 1.36.0
* mutable span in OnEnding, prevent async mutation (a clone rather than the original span is passed to onEnd)
* change composer/tools cache key
cached vendor dir was causing havoc with a conflict between vendor and vendor-bin/psalm (amphp/amp)

* drop metrics string temporality
Temporality|string|null was allowed for temporality to avoid BC in 1.x
convert Temporality to an enum

* convert InstrumentType to enum
- drop string|InstrumentType, which exists in 1.x for forward-compatibility

* add advisory to DefaultAggregationProviderInterface