Option callbacks are now invoked inside prompt and can be used to validate prompt inputs

[Saif807380]

Callbacks used to be invoked for the prompt results, therefore couldn't be used as validators for validating prompt input. Following are the changes made -

• Inlined Parameter.process_value into Parameter.full_process_value
• Renamed full_process_value to process_value
• Moved the if self.callback block from handle_parse_result to the bottom process_value

The current behaviour due to the above changes is as expected to be. The user will be prompted until he/she enters a value deemed valid by the validator callback.

However, this test is failing. From what I understand, process_value gets the value from the prompt when value is None and self.prompt is True. I think that self.prompt_required needs to be used somewhere but I'm not sure where exactly.

I plan to update the docs, once all tests pass.

• Fixes Sanitization for click inputs #457

Checklist:

• Add tests that demonstrate the correct behaviour of the change. Tests should fail without the change.
• Add or update relevant docs, in the docs folder and in code.
• Add an entry in CHANGES.rst summarizing the change and linking to the issue.
• Add .. versionchanged:: entries in any relevant code docs.
• Run pre-commit hooks and fix any issues.
• Run pytest and tox, no tests failed.