Make 'field is not accessible' and 'field initialized twice' errors point to the field inside the obj construction (#24557)

Fixes two line infos to make the error's clearer inside editors

- 'field is not accessible' would point to the whole object construction
instead of just the field inside the construction
- 'field initialized twice' would point to the colon instead of the
field

tests/objects/mobjconstr_msgs.nim

@@ -0,0 +1,3 @@
+type
+  PrivateField* = object
+    priv: string

tests/objects/tobjconstr_msgs.nim

@@ -0,0 +1,23 @@
+discard """
+  cmd: "nim check $file"
+"""
+
+import mobjconstr_msgs
+
+
+block:
+  discard PrivateField(
+    priv: "test" #[tt.Error
+    ^ the field 'priv' is not accessible]#
+  )
+
+
+block:
+  type
+    Foo = object
+      field: string
+  discard Foo(
+    field: "test",
+    field: "test" #[tt.Error
+    ^ field initialized twice: 'field']#
+  )