Add ability to call orig subroutine when we override it

[KES777]

We need some functionality similar to around. This could be useful when we override only particular calls

[exodist]

You can always get the origjnal from the $mock object: https://metacpan.org/pod/Test2::Mock#$mock-%3Eorig($SYMBOL)

Also there is an 'around' method to Test2::Mock, and that is usable in Test2::Tools::Mock which is just candy around it:
https://metacpan.org/pod/Test2::Mock#$mock-%3Earound($NAME,-sub-{-...-})

So this works fine:

use Test2::V0;

{
    package Foo;

    sub blah { 'blah' }
}

my $mock = mock 'Foo' => (
    around => [
        blah => sub {
            my ($orig, $class, @args) = @_; 

            my $got = $class->$orig(@args);

            return "around $got";
        },  
    ]   
);

is(Foo->blah, "around blah", "Mocked foo() and called original inside it");

done_testing;

ok 1 - Mocked foo() and called original inside it
1..1

So maybe the problem is we need more documentation?

[KES777]

yes, would be nice to know list of methods which could be used like override and add. And now I know that around could be used too.