This is kinda messy, because there is no good way to signal to
the compiler that some code uses direct comparison of floating
point numbers intentionally, so instead we have to use diagnostic
pragmas.

We also have to over-suppress the test files, because Clang (and
possibly GCC) still issue warnings from template instantiation
even if the instantion site is under warning suppression, so the
template definition has to be under warning suppression as well.

Closes #2406

The cleanup also found out that custom translation for std-derived
exceptions test wasn't running properly, and fixed that.
We cannot enable the warning globally, because the tests contain
some functions that are unused by design -- e.g. when checking
stringification priority of StringMaker vs range fallback and so
on.

Closes #2392

Co-authored-by: Martin Hořeňovský <martin.horenovsky@gmail.com>

Signed-off-by: Kochetkov, Yuriy <yuriyx.kochetkov@intel.com>

- do not hardcode content of containers
- prefix members with m_
- add const and non-const iterators to `with_mocked_iterator_access`
- remove `m_touched` as it wasn't filled properly and isn't used anyway

Removed:
 * NaN normalization
 * INFINITY normalization
 * errno normalization
 * Completely unused duration regex

Tests using these macros should be tagged `[approvals]`
so they are not run as part of approval tests.

Also simplified regex for the test's executable filename,
and hidden some tests relying on nullptr normalization.