otelconf: add support for OTEL_EXPERIMENTAL_CONFIG_FILE variable

[codeboten]

Component

Config

Problem Statement

As per the spec:

Setting the OTEL_EXPERIMENTAL_CONFIG_FILE environment variable (for languages that support it) provides users a convenient way to initialize OpenTelemetry components without needing to learn language-specific configuration details or use a large number of environment variables. The pattern for accessing the configured components and installing into instrumentation will vary by language. For example, the usage in Java might resemble:

https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk.md#via-otel_experimental_config_file

Proposed Solution

Open to suggestions of how this should be implemented to align w/ the rest of the Go SDK implementation

Alternatives

No response

Prior Art

No response

Additional Context

No response

[codeboten]

After discussing it at the 23-OCT SIG call, the decision is in the short term to include this in an init function in the otelconf package that will automatically configure the SDK components