collation: introduce collation fingerprint

Collation fingerprint is a formatted string unique for a set
of collation properties. Equal collations with different names
have the same fingerprint.

This new property is used to build collation fingerprint cache
to use in Tarantool internals, where collation name does not
matter.

Fingerprint cache can never conflict or replace on insertion into
it. It means, that, for example, utf8 module being created in
this patchset, can fill collation cache with its own collations
and it will affect neither users or other modules.