Sample/form agent

[heiko-hotz]

This pull request introduces the FormAgent, a new specialized agent that demonstrates the extensibility of the core BrowserAgent framework. The FormAgent is designed specifically for filling out web forms by reading structured data from local JSON files, bridging the gap between local data and web interfaces.

This change evolves the project from a single-purpose browser automation tool into a more robust agent framework, where specialised agents can be created by equipping them with custom tools tailored to specific tasks.