Refactor: Add InsufficientFundsError in create_instance

[MHHukiewitz]

• Refactor submit() and broadcast() methods to add raise_on_rejected parameter. This allows client methods to implement their own exception handling on broadcast.
• Implement InsufficientFundsError if creating an instance failed due to low funds.

[github-actions]

The changes in this PR include:

1. Adding a new parameter raise_on_rejected to several methods in aleph-sdk-python. This involves modifying function signatures and updating calls to these functions throughout the codebase.
2. Introducing a new exception InsufficientFundsError in exceptions.py.
3. Adding a new fixture rejected_message in conftest.py for use in testing.
4. Updating several test functions to handle the new raise_on_rejected parameter and the new InsufficientFundsError exception.

These changes introduce complexity at multiple levels of the codebase, including modifications to core functionality, introduction of a new error type, and updates to testing. As such, this PR requires careful review to ensure that these changes do not introduce bugs or unintended side effects.

[1yam]

LGTM