PHP: Numeral syntax improvements (#2701)

Improves numeral literal handling in the Prism PHP component in two ways:

1. Since PHP 7.4, it is possible to use [underscore numeric separator](https://php.watch/versions/7.4/underscore_numeric_separator). Prism correctly handles this for decimal numbers, but not for binary, octal, and hex numerals although PHP supports the underscore separator for binary, octal, and hex numeric literals as well.
2. In upcoming PHP 8.1, PHP supports an [explicit octal numeral prefix `0o`/`0O`](https://php.watch/versions/8.1/explicit-octal-notation). The existing `0` prefix is not removed.

This commit updates the PHP number regex to accommodate both cases above, and expands the tests for new syntax.

Author: Ayesh

components/prism-php.js

@@ -15,7 +15,7 @@
 		/\b[A-Z_][A-Z0-9_]*\b(?!\s*\()/,
 		/\b(?:null)\b/i,
 	];
-	var number = /\b0b[01]+\b|\b0x[\da-f]+\b|(?:\b\d+(?:_\d+)*(?:\.(?:\d+(?:_\d+)*)?)?|\B\.\d+)(?:e[+-]?\d+)?/i;
+	var number = /\b0b[01]+(?:_[01]+)*\b|\b0o[0-7]+(?:_[0-7]+)*\b|\b0x[\da-f]+(?:_[\da-f]+)*\b|(?:\b\d+(?:_\d+)*\.?(?:\d+(?:_\d+)*)?|\B\.\d+)(?:e[+-]?\d+)?/i;
 	var operator = /<?=>|\?\?=?|\.{3}|\??->|[!=]=?=?|::|\*\*=?|--|\+\+|&&|\|\||<<|>>|[?~]|[/^|%*&<>.+-]=?/;
 	var punctuation = /[{}\[\](),:;]/;
 

components/prism-php.min.js

@@ -7,6 +7,13 @@
 0x539
 0x1A
 0123
+0o123
+0O123
+0b1111_0000_111
+0o1111_0000_123
+0O1111_0000_123
+01111_0000_123
+0xAAAA_FFF_0123
 
 ----------------------------------------------------
 
@@ -19,9 +26,16 @@
 	["number", "0b10100111001"],
 	["number", "0x539"],
 	["number", "0x1A"],
-	["number", "0123"]
+	["number", "0123"],
+	["number", "0o123"],
+	["number", "0O123"],
+	["number", "0b1111_0000_111"],
+	["number", "0o1111_0000_123"],
+	["number", "0O1111_0000_123"],
+	["number", "01111_0000_123"],
+	["number", "0xAAAA_FFF_0123"]
 ]
 
 ----------------------------------------------------
 
-Checks for numbers.
+Checks for numbers.