new interface: search_permissions() - access to 06perms.txt

[karenetheridge]

There doesn't seem to be an interface for accessing the 06perms.txt file - it would be useful to have one!

(e.g. in my still-hypothetical [AutoAuthority] dzil plugin.)

Assuming the sort order is correct, this should be relatively trivial to implement.

[karenetheridge]

existing backends include:

• https://metacpan.org/release/PAUSE-Permissions
• https://metacpan.org/release/Parse-CPAN-Perms

and I wouldn't be surprised if the MetaCPAN API exposed this information as well