refactor: hamilton.exceptions

[zilto]

Given the increasing complexity of the library, it could be valuable to create custom exceptions rather than generic ValueError and KeyError.

This helps with:

• readability: the name of the exception is informative EdgeTypeMismatchException, UnknownNodeException, MaterializationError
• maintainability: the exceptions can be gradually improved by modifying the message in a central place instead of attaching custom messages to individual KeyError around the codebase
• debugging: maintainers and users can make a better use of the debugger and exception handling to debug and test their code