Add opentelemetry declarative configuration schema

[jack-berg]

Resolves open-telemetry/opentelemetry-configuration#468.

Context:

• OpenTelemetry declarative configuration is a config interface for OpenTelemetry SDKs, aimed at being language agnostic and more expressive than env vars
• We recently marked it as stable in the opentelemetry specification: Mark declarative config as stable open-telemetry/opentelemetry-specification#4568
• The JSON schema lives in opentelemetry-configuration/opentelemetry_configuration.json

We think it would be a great addition to SchemaStore!

cc @open-telemetry/configuration-approvers (i.e. @tsloughter, @codeboten, @brettmc, @MrAlias, @marcalff)

[github-actions]

Thanks for the PR!

This section of the codebase is owned by @madskristensen and @hyperupcall - if they write a comment saying "LGTM" then it will be merged.

[madskristensen]

Thanks