Build: use attributes to indicate installed script classes

We have two classes of scripts to be installed, those that are
installed as "normal" programs, and those that are installed as "misc"
scripts.  These classes are installed in different locations, so the
build file templates must pay attention.

Because we didn't have the tools to indicate what scripts go where, we
had these scripts hard coded in the build template files, with the
maintenance issues that may cause.  Now that we have attributes, those
can be used to classify the installed scripts, and have the build file
templates simply check the attributes to know what's what.

Furthermore, the 'tsget.pl' script exists both as 'tsget.pl' and
'tsget', which is done by installing a symbolic link (or copy).  This
link name is now given through an attribute, which results in even
less hard coding in the Unix Makefile template.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7581)