add dynamic clients for all APIs

[ashwinb]

What does this PR do?

We have frequently bit-rotten (apis//client.py) files. They have two drawbacks:

• we need to hand-write these client implementations (work!)
• they often are poorly written and untested
• they are accompanied with some useful testing code which is useful for developers but not intended for end users.

This PR is the first step towards killing these hand-written implementations. It dynamically creates Client classes for each API protocol and registers appropriate methods based on type introspection.

Test Plan

First, I ran an ollama server (ollama run llama3.2:3b-instruct-fp16) and then started a Llama Stack using --template ollama on port 5003.

Then I set up the following yaml for testing:

providers:
 - provider_id: remote
   provider_type: remote
   config: 
     host: localhost
     port: 5003

Then I ran the following set of tests:

MODEL_IDS=Llama3.2-3B-Instruct \
PROVIDER_ID=remote \
PROVIDER_CONFIG=config.yaml \
$CONDA_PREFIX/bin/pytest -s llama_stack/providers/tests/inference/test_inference.py

PROVIDER_ID=remote \
PROVIDER_CONFIG=config.yaml \
$CONDA_PREFIX/bin/pytest -s llama_stack/providers/tests/memory/test_memory.py

Then I modified the config.yaml to be:

providers:
  inference:
  - provider_id: remote
    provider_type: remote
    config:
      host: localhost
      port: 5003
  safety:
  - provider_id: remote
    provider_type: remote
    config:
      host: localhost
      port: 5003
  memory:
  - provider_id: remote
    provider_type: remote
    config:
      host: localhost
      port: 5003
  agents:
  - provider_id: remote
    provider_type: remote
    config:
      host: localhost
      port: 5003

And ran the following tests:

MODEL_ID=Llama3.2-3B-Instruct \
PROVIDER_ID=remote \
PROVIDER_CONFIG=config.yaml \
$CONDA_PREFIX/bin/pytest -s llama_stack/providers/tests/agents/test_agents.py

This test did not fully pass due to an unexpected model response from the ollama 3b-instruct llama model w.r.t. tool calling but tests which didn't exercise tool calling passed.

[ashwinb]

FINALLY! we actually type-hint it in the way it is supposed to be.

This might become an issue with our OpenAPI generator, but we will fix that downstream. Our source must be always correct.

[ashwinb]

I will be deleting this code later since someone is going to stumble on this and use it inadvertently again

[ashwinb]

this looks bad though uh oh, need to check