[RFC] Support object types in BCMath (#13741)

Added BcMath\Number class. It is an immutable object, has methods that are
equivalent to existing BCMath calculation functions, and can also be calculated
using operators.

The existing BCMath function returned a string for each calculation, but this
class returns an object.

RFC: https://wiki.php.net/rfc/support_object_type_in_bcmath,
https://wiki.php.net/rfc/fix_up_bcmath_number_class

---------

Co-authored-by: Niels Dossche <[email protected]>

Author: SakiTakamachi

NEWS

@@ -5,6 +5,7 @@ PHP                                                                        NEWS
 - BCMath:
   . Fixed LONG_MAX in BCMath ext. (Saki Takamachi)
   . Fixed bcdiv() div by one. (Saki Takamachi)
+  . [RFC] Support object types in BCMath. (Saki Takamachi)
 
 - Core:
   . Fixed bug GH-15330 (Do not scan generator frames more than once). (Arnaud)

UPGRADING

@@ -873,6 +873,15 @@ PHP 8.4 UPGRADE NOTES
 7. New Classes and Interfaces
 ========================================
 
+- BCMath:
+  . Added BcMath\Number class. It is an immutable object, has methods that are
+    equivalent to existing BCMath calculation functions, and can also be calculated
+    using operators.
+    The existing BCMath function returned a string for each calculation, but this
+    class returns an object.
+    RFC: https://wiki.php.net/rfc/support_object_type_in_bcmath,
+    https://wiki.php.net/rfc/fix_up_bcmath_number_class
+
 - Core:
   . New RequestParseBodyException.
     RFC: https://wiki.php.net/rfc/rfc1867-non-post