Add wildcard matcher tests

[felixbarny]

This extracts some of the wildcard matcher tests from the Java agent to a format that should be verified by all agents when implementing the wildcard matcher for #144

[felixbarny]

@elastic/observablt-robots could you set up automation, similar to the one for the gherkin-specs folder, that syncs up the json-specs folder to the agent repos by creating PRs?

[felixbarny]

Dear @elastic/apm-agent-devs

Please specify in which directory you want the json-specs folder to be synced to.

Agent	Path
.NET
Go	internal/testdata/json-specs
Java	apm-agent-core/src/test/resources/json-specs
Node.js
PHP	tests/APM_Agents_shared/json-specs
Python	tests/upstream/json-specs
Ruby	spec/fixtures/

This is the current destination of the gherkin-specs folder: https://github.com/elastic/apm/blob/master/.ci/.jenkins-agents.yml

[mdelapenya]

Hey @felixbarny, we finished (and polished) the automation for the PRs, so I think we can merge this and manually trigger the build (see #324)

BTW, the PHP agent does not have an entry for Gherkin specs, should it be added, and implemented in the agent end?

[felixbarny]

BTW, the PHP agent does not have an entry for Gherkin specs, should it be added, and implemented in the agent end?

The PHP agent is not GA yet. But yes, eventually also the PHP agent should be added. I've created follow up issues for .NET and PHP.