Explicitly disallow implicit casting of ObjectPtr to bool to match
clang's and MSVC's behavior.
Introduce a few function overloads using ObjectPtr instead of Object*.
Fix printing of ObjectPtr for objects-printer.cc and GTest.

Bug: v8:3770
Change-Id: I3c3580d363ae6d9fe8f743c6151abc11a915f05c
Reviewed-on: https://chromium-review.googlesource.com/c/1351245
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57928}