Allow android::base::ScopeGuard in STL containers

This change lets android::base::ScopeGuard be useful in STL containers
(e.g. std::vector<android::base::ScopeGuard<std::function<void()>>>). It
also provides perfect forwarding for android::base::make_scope_guard.

Bug: 34764308
Test: libbase_test

Change-Id: I7d1e5494b0f0695763cff0700efdb9ec18ae85c8
Merged-In: I7d1e5494b0f0695763cff0700efdb9ec18ae85c8
(cherry picked from commit b77035b8)