Fix parser translator scope issues for implicit hash values

`builder.pair_label` is no good since it makes use of variables that the parser gem encountered.
Since the prism translator doesn't keep proper track of that information, the following code interprets
the implicit value as a local variable, even though it is not in scope:

```rb
def foo
  bar = 123
end

{ bar: }
```

Author: Earlopain

lib/prism/translation/parser/compiler.rb

@@ -150,14 +150,17 @@ def visit_assoc_node(node)
               builder.pair_quoted(token(key.opening_loc), [builder.string_internal([key.unescaped, srange(key.value_loc)])], token(key.closing_loc), visit(node.value))
             end
           elsif node.value.is_a?(ImplicitNode)
-            if (value = node.value.value).is_a?(LocalVariableReadNode)
-              builder.pair_keyword(
-                [key.unescaped, srange(key)],
-                builder.ident([value.name, srange(key.value_loc)]).updated(:lvar)
-              )
+            value = node.value.value
+
+            implicit_value = if value.is_a?(CallNode)
+              builder.call_method(nil, nil, [value.name, srange(value.message_loc)])
+            elsif value.is_a?(ConstantReadNode)
+              builder.const([value.name, srange(key.value_loc)])
             else
-              builder.pair_label([key.unescaped, srange(key.location)])
+              builder.ident([value.name, srange(key.value_loc)]).updated(:lvar)
             end
+
+            builder.pair_keyword([key.unescaped, srange(key)], implicit_value)
           elsif node.operator_loc
             builder.pair(visit(key), token(node.operator_loc), visit(node.value))
           elsif key.is_a?(SymbolNode) && key.opening_loc.nil?