Add more smoke test and framework how to add more tests

[pavolloffay]

Add smoke tests for gRPC and different servlet containers (similar to https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/master/smoke-tests/matrix).

The images for these should be in control of this project, build as part of the smoke-test job. It should be easy to add smoke tests for new frameworks.

[pavolloffay]

We can certainly adopt OTEL smoke tests, my requirements are:

• test capturing of payloads
• test capturing of headers
• the test images should be built and published to HT docker registry - e.g. ghcr or dockerhub

[samarth-gupta-traceable]

@pavolloffay here the 2 steps I propose to integrate and modify OTEL smoke test with HT java agent:

1. Import current test from OTEL to HT repo and make sure all test are passing with hypertrace-agent-all.jar . This will require changes in smoke test as well as gradle files. This will include changes for publishing images to HT docker registry.
2. Enhance test app to send POST requests with required headers & add validation by enhancing test.