[Py]Initialization and Configuration

[tanyasingh1902]

Create the DotpromptOptions class to hold configuration settings.
This involves defining attributes for default model, model configurations, helpers, partials, tools, resolvers (tool, schema, partial), and schemas.

Create the Dotprompt class with its constructor.
Initialize the Handlebars engine.
Store configuration options from DotpromptOptions.
Register default helper functions.
Register custom helpers and partials from the options.