Add SLO test workload and CI

[zeruk]

CI example is here: https://github.com/ydb-platform/ydb-nodejs-sdk/blob/main/.github/workflows/slo.yml Workload sample and description is here: https://github.com/ydb-platform/ydb-nodejs-sdk/tree/main/slo-workload As you can see from the repository, you will need to create a directory for the workload package and provide a Dockerfile inside it.

Important note: Do not run SLO tests in pull requests. You will either have to open secrets for pull requests, or give rights to each contributor (which is not a safe method either). The way I see it, the best option is to run tests on the main branch