Cross-agent unit testing for Azure Instrumentations

The Azure Instrumentations are all built around a REST API. In practice, this means there are generally large `if`-statement blocks that set the operation name and resource based on various pieces of the REST request. (See https://github.com/elastic/apm-agent-python/pull/1316 for examples in Python)

@beniwohli [pointed out](https://github.com/elastic/apm-agent-python/pull/1316#pullrequestreview-768750495) that it would be useful to encode [the tables in the spec](https://github.com/elastic/apm/blob/master/specs/agents/tracing-instrumentation-azure.md) into JSON such that unit tests could be constructed to ensure consistency across agents.