feat(LLM.php): add abstract call method to LLM class

feat(llm-LLaMACpp.php): add example usage of LLaMACpp class with a prompt text

feat(LLaMACpp.php): add LLaMACpp class implementation with constructor, defaultParams, call, llmType, toArray, and getIdentifyingParams methods.

refactor(Document.php): use PHP_EOL constant instead of "\n\n" string…

… literal in paragraphs method