remove or factor out the @index listing from Padre::HelpProvider::Perl

[szabgab]

I think the hard-coded list of all the keywords is not the maintainable way to go so probably that list should be read from somewhere.

[szabgab]

Also there is a strange hash called Type that is not declared but probably imported from Pod::Functions. If that is really needed than we better write

use Pod::Functions qw(%Type);

for the sanity of the next reader.