Make IntlDateFormatter ctor $pattern nullable

The implementation already made this argument nullable, but it
was not reflected in the stub.

Generate ext/intl class entries from stubs

Closes GH-6670

Verify parameter names of function aliases

Closes GH-6335

Improve parameter names in ext/intl

Closes GH-6309

More precise type information for datefmt_format()

Display types in stubs more uniformly

In preparation for generating method signatures for the manual.

This change gets rid of bogus false|null return types, a few unnecessary traili

Display types in stubs more uniformly

In preparation for generating method signatures for the manual.

This change gets rid of bogus false|null return types, a few unnecessary trailing backslashes, and settles on using ? when possible for nullable types.

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Declare array|int and object-of-class|int types in stubs

Closes GH-6081

Co-Authored-By: Nikita Popov <nikic@php.net>

Use ZPP instead of custom type checks

We can add these types as a native type declaration to stubs as a side-effect. Closes GH-6068

Add more precise type info for stubs

Closes GH-6005

Add another round of missing parameter types to stubs

Closes GH-5950

Add a bunch of missing argument types to stubs

Warning to ValueError promotion in Intl extension Part 1

Affects:
- IntlCalendar
- IntlGregorianCalendar
- IntlBreakIterator

Closes GH-5669

Add a few missing parameter types in stubs

Related to GH-5627

Fix IntlGregorianCalendar constructor signature

Give these conversative UNKNOWN defaults and no types, as the
overload is something of a mess.

Fix some UNKNOWN default values

In ext/ffi, ext/intl, ext/mysqli, and ext/pcntl

Generate method entries for ext/intl

Closes GH-5370

Fix the default value of the $length parameter of grapheme_substr()

Do not include the same stub multiple times

Closes GH-5322