variant printing is ambiguous

In https://github.com/google/googletest/issues/1151 I proposed a variant printing implementation. The one that ended up landing was unfortunately ambiguous because it prints the type name and type names are never guaranteed to be unique in a variant, least of all their actual spelling.

Propose replacing it with the type index, although pragmatically it's useful to additionally include the type name as we're currently doing.

Start by reading the proposed implementation and discussion in issue #1151, then locate the current variant printing entry point. Verify how the existing type name is produced and update the expected output so the type index distinguishes alternatives while retaining the type name.

Written by the indexing model from the issue text.