invoke type casts default values

[davidism]

#2085 reverted applying type casting when getting defaults, casting was only done when processing the values. However, invoke also relies on getting defaults, so it also needs to cast the values.

• fixes multiple=True on the option no longer produces empty tuple when using ctx.invoke #2089
• fixes Type conversion no longer applied to defaults when invoking a default subcommand in 8.0.2 #2090

Checklist:

• Add tests that demonstrate the correct behavior 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.