Lm-format-enforcer

- Improved JsonSchemaParser whitespace support
- Improved RegexParser performance, especially in regular expressions with `.+` and `.*` sections.

- Modified example in main README to be able to run end to end in Google Colab

- Added integration with the `LlamaIndex` library (huggingface and llama.cpp backends) via sample notebook.

- Introduced lmformatenforcer.integrations module which will have the integrations with inference engines.
- Added llama-cpp-python integration to the library in lmformatenforcer.integrations.llamacpp
- Breaking API Change: Moved 'build_transformers_prefix_allowed_tokens_fn',
'generate_enforced' from lmformatenforcer to lmformatenforcer.integrations.transformers.