feat(sdk): add MissingDependencyError for declarative configuration

[dharaneeshexe-web]

Changes

Adds a structured \MissingDependencyError\ (subclass of \ConfigurationError) that generates a descriptive pip install message when an optional dependency is missing. Replaces ad-hoc \ConfigurationError\ / \ImportError\ raises across all declarative config providers.

Key changes:

• **_exceptions.py**: Added \MissingDependencyError\ with \package, \eature, \install_name, \extras\ parameters and auto-generated pip install message
• **_tracer_provider.py*, **_logger_provider.py*, **_meter_provider.py**: OTLP HTTP/gRPC exporter and Prometheus reader dependency checks now raise \MissingDependencyError\
• **\ile/_loader.py**: yaml/jsonschema import guards now raise \MissingDependencyError\
• **\ile/init.py**: Added \MissingDependencyError\ to re-exports
• **\ est_exceptions.py**: 7 unit tests covering subclass check, minimal constructor, feature message, custom install_name, extras, and catch-as-ConfigurationError
• **.changelog/5229.added**: Towncrier fragment

Closes #5229
Refs #3631

[linux-foundation-easycla]

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• ✅ login: dharaneeshexe-web / name: dharaneesh (3abac05)

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