Add new LLM Picker for the new Builder.
### Changes 🏗️
- Enrich `LlmModelMeta` (in `llm.py`) with human readable model, creator
and provider names and price tier (note: this is temporary measure and
all LlmModelMeta will be removed completely once LLM Registry is ready)
- Add provider icons
- Add custom input field `LlmModelField` and its components&helpers
### Checklist 📋
#### For code changes:
- [x] I have clearly listed my changes in the PR description
- [x] I have made a test plan
- [x] I have tested my changes according to the test plan:
- [x] LLM model picker works correctly in the new Builder
- [x] Legacy LLM model picker works in the old Builder
ebabc4287e
