Inject spinner instance as parameter to decorated function

[romnn]

I propose to inject the spinner instance as an optional parameter to functions decorated by halo. This was my use case:

@Halo(text='Doing work', spinner='dots', color="red")
def initialize_git(spinner=None):  # This argument is optional and can also be omitted
    try:
        my_complicated_function()
    except Exception:
        spinner.fail("Failed!")
        raise
    spinner.succeed("Succeeded!")

I know that this is possible to use a context manager, but this does require deeper nesting and is not that neat imo. Please let me know if you consider this a valid use case.

Description

This PR adds functionality to declare the optional keyword argument as a parameter to obtain a reference to the spinner object. This does not break anything and is completely optional.

Checklist

• Your branch is up-to-date with the base branch
• You've included at least one test if this is a new feature
• All tests are passing

Further considerations

It is also possible to inject the spinner instance as a positional argument, but this could not be made optional.

[coveralls]

Pull Request Test Coverage Report for Build 424

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at ?%

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Totals
Change from base Build 422:	0.0%
Covered Lines:
Relevant Lines:	0

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💛 - Coveralls