[dynamic control] Create providers from SourceKind

[jackshirazi]

Description:

This adds getting PolicyProviders of specific implementations from SourceKind

Existing Issue(s):

#2546

Testing:

Added

Documentation:

To be added

Outstanding items:

Wiring up the policy pipeline:

• message -> provider -> policy -> policy handler -> implementer
• eg change sampling rate message -> OpampPolicyprovider -> TraceSamplingRatePolicy -> PolicyStore -> TraceSamplingRatePolicyImplementer

Steps needed for the wiring:

• providers reading policies, eg OpampPolicyprovider
• implementers applying policies, eg a TraceSamplingRatePolicyImplementer
• policy structures (eg TraceSamplingRatePolicy) that the provider converts messages into
• registering config to policy structures (eg "trace_sampling_rate_policy" registered to TraceSamplingRatePolicy)
• initializing policy classes (eg TraceSamplingRatePolicy needs to install a custom sampler)
• activate configured providers (eg start OpampPolicyprovider reading from it's source)
• register implementers for policies (eg a new TraceSamplingRatePolicy is applied by a TraceSamplingRatePolicyImplementer)
• link the provider to processing policies and applying implementers

[Copilot]

Pull request overview

Adds initial wiring to instantiate PolicyProvider implementations directly from SourceKind, enabling future policy pipeline setup for dynamic-control.

Changes:

• Extend SourceKind with a per-kind provider factory and a createProvider(...) method.
• Add OPAMP provider creation via OpampPolicyProvider when a location key is provided.
• Add unit tests covering provider creation behavior and null-argument validation.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/source/SourceKind.java	Introduces provider factory dispatch on enum constants and adds OPAMP provider creation.
dynamic-control/src/test/java/io/opentelemetry/contrib/dynamic/policy/source/SourceKindTest.java	Adds tests for createProvider(...) behavior across kinds and argument validation.