* Update load test template and config generation.
This change includes the following features and fixes:
* Add a script to generate load test examples.
* Update template generation logic to support round trip from configs to templates (handling of repeated clients and servers for the same language and of named clients and servers in source configs).
* Integrate safe language names from scenario config.
* Update template and config formatting (now that we generate in round trip).
* Fix shellcheck lint warnings.
* Update README.md.
This commit includes the following changes:
1. A new load test template generator (loadtest_template.py) is added. The template generator combines existing configurations or templates for several languages into a single template that can be used to generate configurations for different languages or combinations of languages.
2. A basic template generated from the example tests in grpc/test-infra (loadtest_template_basic_all_languages.yaml) is added.
3. The load test config generator is updated to use the combined template.
4. An example run consisting of a single test (generated from the combined template) is added and set up to run continuously.
This removes all of the node code and tests from the repo, along with the
scripts for running Node unit tests, performance tests, and artifact builds.
The scripts for running tests from the grpc-node repository are untouched.