[Feature #19719] Universal Parser

Introduce Universal Parser mode for the parser.
This commit includes these changes:

* Introduce `UNIVERSAL_PARSER` macro. All of CRuby related functions
  are passed via `struct rb_parser_config_struct` when this macro is enabled.
* Add CI task with 'cppflags=-DUNIVERSAL_PARSER' for ubuntu.

parser_value.h

@@ -0,0 +1,106 @@
+#ifndef EXTERNAL_VALUE_H
+#define EXTERNAL_VALUE_H
+
+#include "ruby/config.h"
+
+#if defined(__DOXYGEN__)
+
+/**
+ * Type that represents a Ruby object.  It is an unsigned integer of some kind,
+ * depending on platforms.
+ *
+ * ```CXX
+ * VALUE value = rb_eval_string("ARGF.readlines.map.with_index");
+ * ```
+ *
+ * @warning  ::VALUE is not a pointer.
+ * @warning  ::VALUE can be wider than `long`.
+ */
+typedef uintptr_t VALUE;
+
+/**
+ * Type that represents a Ruby identifier such as a variable name.
+ *
+ * ```CXX
+ * ID method = rb_intern("method");
+ * VALUE result = rb_funcall(obj, method, 0);
+ * ```
+ *
+ * @note  ::rb_cSymbol is a Ruby-level data type for the same thing.
+ */
+typedef uintptr_t ID;
+
+/**
+ * A signed integer type that has the same width with ::VALUE.
+ *
+ * @internal
+ *
+ * @shyouhei wonders: is it guaranteed  that `uintptr_t` and `intptr_t` are the
+ * same width?  As far as I read ISO/IEC 9899:2018 section 7.20.1.4 paragraph 1
+ * no such description is given... or defined elsewhere?
+ */
+typedef intptr_t SIGNED_VALUE;
+
+/**
+ * Identical to  `sizeof(VALUE)`, except it  is a macro  that can also  be used
+ * inside of preprocessor directives such as `#if`.  Handy on occasions.
+ */
+#define SIZEOF_VALUE SIZEOF_UINTPTR_T
+
+/**
+ * @private
+ *
+ * A compile-time constant of type ::VALUE whose value is 0.
+ */
+#define RBIMPL_VALUE_NULL UINTPTR_C(0)
+
+/**
+ * @private
+ *
+ * A compile-time constant of type ::VALUE whose value is 1.
+ */
+#define RBIMPL_VALUE_ONE  UINTPTR_C(1)
+
+/**
+ * @private
+ *
+ * Maximum possible value that a ::VALUE can take.
+ */
+#define RBIMPL_VALUE_FULL UINTPTR_MAX
+
+#elif defined HAVE_UINTPTR_T && 0
+typedef uintptr_t VALUE;
+typedef uintptr_t ID;
+# define SIGNED_VALUE intptr_t
+# define SIZEOF_VALUE SIZEOF_UINTPTR_T
+# undef PRI_VALUE_PREFIX
+# define RBIMPL_VALUE_NULL UINTPTR_C(0)
+# define RBIMPL_VALUE_ONE  UINTPTR_C(1)
+# define RBIMPL_VALUE_FULL UINTPTR_MAX
+
+#elif SIZEOF_LONG == SIZEOF_VOIDP
+typedef unsigned long VALUE;
+typedef unsigned long ID;
+# define SIGNED_VALUE long
+# define SIZEOF_VALUE SIZEOF_LONG
+# define PRI_VALUE_PREFIX "l"
+# define RBIMPL_VALUE_NULL 0UL
+# define RBIMPL_VALUE_ONE  1UL
+# define RBIMPL_VALUE_FULL ULONG_MAX
+
+#elif SIZEOF_LONG_LONG == SIZEOF_VOIDP
+typedef unsigned LONG_LONG VALUE;
+typedef unsigned LONG_LONG ID;
+# define SIGNED_VALUE LONG_LONG
+# define LONG_LONG_VALUE 1
+# define SIZEOF_VALUE SIZEOF_LONG_LONG
+# define PRI_VALUE_PREFIX PRI_LL_PREFIX
+# define RBIMPL_VALUE_NULL 0ULL
+# define RBIMPL_VALUE_ONE  1ULL
+# define RBIMPL_VALUE_FULL ULLONG_MAX
+
+#else
+# error ---->> ruby requires sizeof(void*) == sizeof(long) or sizeof(LONG_LONG) to be compiled. <<----
+#endif
+
+#endif /* EXTERNAL_VALUE_H */