chore(tests/lean/run/matrix): simplify same_dim_irrel proof

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/pp_options): use a more effective get_distinguishing_pp_options

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(doc/authors.md): update authors.md page

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>