Make manuals with TYPE conform with man-pages(7)

Make manuals with TYPE conform with man-pages(7)

Details from man-pages(7) that are used:

    Formatting conventions for manual pages describing functions

        ...
        Variable names should, like argument names, be specified in italics.
        ...

    Formatting conventions (general)

        ...
        Special macros, which are usually in uppercase, are in bold.
        Exception: don't boldface NULL.
        ...

Furthermore, for TYPE used as a placeholder for types and correponding
part of function names, we extrapolate that it's both a type and a
variable, and should therefore be bold (typical for types and function
names) and italic (typical for variables).  POD processors don'e know
this, so we have to help them along.  Therefore:

   SPARSE_ARRAY_OF(TYPE)        => B<SPARSE_ARRAY_OF>(B<I<TYPE>>)
   ossl_sa_TYPE_num()           => B<ossl_sa_I<TYPE>_num>()
   TYPE                         => B<I<TYPE>>

There are some other less typical uses where one simply has to give
formatting some extra though.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10041)