feat(config): Add TracerProvider support for declarative config (#4985)

* config: add resource and propagator creation from declarative config

Implements create_resource() and create_propagator()/configure_propagator()
for the declarative file configuration. Resource creation does not read
OTEL_RESOURCE_ATTRIBUTES or run any detectors (matches Java/JS SDK behavior).
Propagator configuration always calls set_global_textmap to override Python's
default tracecontext+baggage, setting a noop CompositePropagator when no
propagator is configured.

Assisted-by: Claude Sonnet 4.6

* update changelog with PR number

Assisted-by: Claude Sonnet 4.6

* fix pylint, pyright and ruff errors in resource/propagator config

- _resource.py: refactor _coerce_attribute_value to dispatch table to
  avoid too-many-return-statements; fix short variable names k/v ->
  attr_key/attr_val; fix return type of _sdk_default_attributes to
  dict[str, str] to satisfy pyright
- _propagator.py: rename short variable names e -> exc, p -> propagator
- test_resource.py: move imports to top level; split TestCreateResource
  (25 methods) into three focused classes to satisfy too-many-public-methods
- test_propagator.py: add pylint disable for protected-access

Assisted-by: Claude Sonnet 4.6

* address review feedback: use _DEFAULT_RESOURCE, fix bool_array coercion

- replace _sdk_default_attributes() with _DEFAULT_RESOURCE from resources module
- move _coerce_bool into dispatch tables for both scalar and array bool types,
  fixing a bug where bool_array with string values like "false" would coerce
  incorrectly via plain bool() (non-empty string -> True)
- add test for bool_array with string values to cover the bug

Assisted-by: Claude Sonnet 4.6

* fix linter

* address review feedback: single coercion table, simplify attributes merge

- collapse _SCALAR_COERCIONS and _ARRAY_COERCIONS into a single _COERCIONS
  dict using an _array() factory, reducing _coerce_attribute_value to two lines
- process attributes_list before attributes so explicit attributes naturally
  overwrite list entries without needing an explicit guard

Assisted-by: Claude Sonnet 4.6

* use Callable type annotation on _array helper

Assisted-by: Claude Sonnet 4.6

* add detection infrastructure foundations for resource detectors

Adds _run_detectors() stub and _filter_attributes() to create_resource(),
providing the shared scaffolding for detector PRs to build on. Detectors
are opt-in: nothing runs unless explicitly listed under
detection_development.detectors in the config. The include/exclude
attribute filter mirrors other SDK behaviour.

Assisted-by: Claude Sonnet 4.6

* move service.name default into base resource

Merges service.name=unknown_service into base before running detectors,
so detectors (e.g. service) can override it. Previously it was added to
config_attrs and merged last, which would have silently overridden any
detector-provided service.name.

Assisted-by: Claude Sonnet 4.6

* remove unused logging import from _propagator.py

Assisted-by: Claude Sonnet 4.6

* add TracerProvider creation from declarative config

Implements create_tracer_provider() and configure_tracer_provider() for
the declarative configuration pipeline (tracking issue #3631 step 5).

Key behaviors:
- Never reads OTEL_TRACES_SAMPLER or OTEL_SPAN_*_LIMIT env vars; absent
  config fields use OTel spec defaults (matching Java SDK behavior)
- Default sampler is ParentBased(root=ALWAYS_ON) per the OTel spec
- SpanLimits absent fields use hardcoded defaults (128) not env vars
- configure_tracer_provider(None) is a no-op per spec/Java/JS behavior
- OTLP exporter fields pass None through so the exporter reads its own
  env vars for unspecified values
- Lazy imports for optional OTLP packages with ConfigurationError on missing
- Supports all 4 ParentBased delegate samplers

Assisted-by: Claude Sonnet 4.6

* add changelog entry for PR #4985

Assisted-by: Claude Sonnet 4.6

* fix CI lint/type failures in tracer provider config

- add # noqa: PLC0415 to lazy OTLP imports (ruff also enforces this)
- move SDK imports to top-level (BatchSpanProcessor, etc.)
- convert test helper methods to @staticmethod to satisfy no-self-use
- add pylint: disable=protected-access for private member access in tests
- fix return type annotation on _create_span_processor

Assisted-by: Claude Sonnet 4.6

* fix pylint no-self-use on TestCreateSampler._make_provider

Assisted-by: Claude Sonnet 4.6

* use allowlist for bool coercion in declarative config resource

Assisted-by: Claude Sonnet 4.6

* address review feedback: simplify resource filter and propagator loading

Assisted-by: Claude Sonnet 4.6

* fix ruff formatting

Assisted-by: Claude Sonnet 4.6

* fix pyright: wrap EntryPoints in iter() for next() compatibility

Assisted-by: Claude Sonnet 4.6