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

tests/debugger/do_variables.expected

@@ -9,6 +9,7 @@ f            | Function  |
 addX         | Function  |           
 z            | undefined | undefined 
 c            | undefined | undefined 
+createRealm  | Function  |           
 resourceName | Function  |           
 print        | Function  |           
 gc           | Function  |           
@@ -21,6 +22,7 @@ f            | Function  |
 addX         | Function  |           
 z            | undefined | undefined 
 c            | undefined | undefined 
+createRealm  | Function  |           
 resourceName | Function  |           
 print        | Function  |           
 gc           | Function  |           
@@ -48,6 +50,7 @@ f            | Function |
 addX         | Function |       
 z            | Number   | 5     
 c            | Number   | 4     
+createRealm  | Function |       
 resourceName | Function |       
 print        | Function |       
 gc           | Function |       
@@ -68,6 +71,7 @@ f            | Function |
 addX         | Function |       
 z            | Number   | 5     
 c            | Number   | 4     
+createRealm  | Function |       
 resourceName | Function |       
 print        | Function |       
 gc           | Function |