Implement realm object and support realms for built-ins and JS functions (#4354)

- Type for realm objects is introduced (ecma_global_object_t)
- Realm reference is added to built-in objects and ECMAScript functions
- Resolving built-ins, global environments, and scopes require realm object
- Unnecessary global object accesses are removed from the code

Missing: external functions and static snapshot functions have no realm reference

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

jerry-core/api/jerry-snapshot.h

@@ -45,7 +45,8 @@ typedef enum
 {
   /* 8 bits are reserved for dynamic features */
   JERRY_SNAPSHOT_HAS_REGEX_LITERAL = (1u << 0), /**< byte code has regex literal */
-  JERRY_SNAPSHOT_HAS_CLASS_LITERAL = (1u << 1), /**< byte code has class literal */
+  JERRY_SNAPSHOT_HAS_REALM_VALUE = (1u << 1), /**< byte code has realm value */
+  JERRY_SNAPSHOT_HAS_CLASS_LITERAL = (1u << 2), /**< byte code has class literal */
   /* 24 bits are reserved for compile time features */
   JERRY_SNAPSHOT_FOUR_BYTE_CPOINTER = (1u << 8) /**< deprecated, an unused placeholder now */
 } jerry_snapshot_global_flags_t;