fdisk: add support for parttype aliases

fdisk: add support for parttype aliases

* add list of supported aliases to 'l' and 'L' output
* support aliases in 't' dialog

For example (use 'swap' to set 0x82 partition type):

 Command (m for help): t
 Selected partition 1
 Hex code or alias (type L to list all): swap
 Changed type of partition 'Linux' to 'Linux swap / Solaris'.

Note that the aliases are evaluated as the last possibility if user's
input dues not match up with any partition type. This is necessary for
backward compatibility.

This patch does NOT introduce shortcuts (.e.g. 'S' for swap) to
fdisk(8) due to collisions with already used dialog keys.

Addresses: https://github.com/karelzak/util-linux/issues/958
Signed-off-by: Karel Zak <kzak@redhat.com>