Related to GH-6701

Closes GH-6696

This deprecates passing null to non-nullable scale arguments of
internal functions, with the eventual goal of making the behavior
consistent with userland functions, where null is never accepted
for non-nullable arguments.

This change is expected to cause quite a lot of fallout. In most
cases, calling code should be adjusted to avoid passing null. In
some cases, PHP should be adjusted to make some function arguments
nullable. I have already fixed a number of functions before landing
this, but feel free to file a bug if you encounter a function that
doesn't accept null, but probably should. (The rule of thumb for
this to be applicable is that the function must have special behavior
for 0 or "", which is distinct from the natural behavior of the
parameter.)

RFC: https://wiki.php.net/rfc/deprecate_null_to_scalar_internal_arg

Closes GH-6475.

This makes --verify also check @implementation-alias. Failures are
ignored using @no-verify instead. Some mistakes have been made that
would have been caught by this...

Closes GH-6615.

We're starting to see a mix between uses of zend_bool and bool.
Replace all usages with the standard bool type everywhere.

Of course, zend_bool is retained as an alias.

Closes GH-6264

Not all extensions consistently throw exceptions when the user passes
a path name containing null bytes. Also, some extensions would throw
a ValueError while others would throw a TypeError. Error messages
also varied.

Now a ValueError is thrown after all failed path checks, at least for
as far as these occur in functions that are exposed to userland.

Closes GH-6216.

Closes GH-6170

This should fix most of the remaining issues with tabs and spaces
being mixed in tests.