Fix values shown for wrong option

[ZanyMonk]

When completing option values, only values corresponding to the option being completed should be shown.

Following exemples are based on a command looking like this:

@click.command()
@click.option('-a', type=click.Choice(['a_val1', 'a_val2']))
@click.option('-b', type=click.Choice(['b_val1', 'b_val2']))
def cli():
    pass

Before

> cmd -a <TAB>
               a_val1
               a_val2
               b_val1
               b_val2

After

> cmd -a <TAB>
               a_val1
               a_val2

[auvipy]

@GhostOps77 can you try and review it please?

[GhostOps77]

@auvipy yep, everything looks good and works well as expected!
No issues in here
You can merge this PR