feat(initializeFunctionsAgent.js): add support for openai-functions agent type
feat(askGPTPlugins.js): change default agent to functions and skip completion
feat(cleanupPreset.js): change default agent to functions and skip completion
feat(getDefaultConversation.js): change default agent to functions and skip completion
feat(handleSubmit.js): change default agent to functions and skip completion
* style(FunctionsAgent.js): remove unnecessary comments and update PREFIX variable
refactor(initializeFunctionsAgent.js): update to use initializeAgentExecutorWithOptions
deps(package.json): update langchain to v0.0.95
refactor(askGPTPlugins.js): pass endpointOption to onStart function
* fix(ChatAgent.js): handle undefined delta content in progressMessage.choices array