ART: Add support for runtime debug checks

Add support for runtime-switchable debug flags. These flags are only
enabled in debug mode, and a constexpr false in release mode. This
allows to distinguish fast from slow checks, for example.

To simplify usage, two macros should be used. DECLARE_RUNTIME_DEBUG_FLAG
defines a static class member or constexpr as the flag. DEFINE_RUNTIME_DEBUG_FLAG
defines the static storage and registers it, if needed. See the
documentation in logging.h.

As is, runtime checks are disabled by default. Pass -XX:SlowDebug=true
to enable them on startup.

Add logging_test. Fix up tests and scripts to enable slow debug checks.

Bug: 35644369
Test: m test-art-host
Change-Id: Icc1cb0bb921d863514c55abef794c5c96f8af801