[lldb][LocateModuleCallback] Update SBFileSpec/SBModuleSpec

RFC https://discourse.llvm.org/t/rfc-python-callback-for-target-get-module/71580

SBFileSpec and SBModuleSpec will be used for locate module callback as Python
function arguments. This diff allows these things.
- Can be instantiated from SBPlatform.
- Can be passed to/from Python.
- Can be accessed for object offset and size.

Differential Revision: https://reviews.llvm.org/D153733

lldb/test/API/python_api/module_spec/TestModuleSpec.py

@@ -0,0 +1,24 @@
+"""
+Test some SBModuleSpec APIs.
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+
+
+class ModuleSpecAPIsTestCase(TestBase):
+    def test_object_offset_and_size(self):
+        module_spec = lldb.SBModuleSpec()
+        self.assertEqual(module_spec.GetObjectOffset(), 0)
+        self.assertEqual(module_spec.GetObjectSize(), 0)
+
+        module_spec.SetObjectOffset(4096)
+        self.assertEqual(module_spec.GetObjectOffset(), 4096)
+
+        module_spec.SetObjectSize(3600)
+        self.assertEqual(module_spec.GetObjectSize(), 3600)
+
+        module_spec.Clear()
+        self.assertEqual(module_spec.GetObjectOffset(), 0)
+        self.assertEqual(module_spec.GetObjectSize(), 0)