[lldb/Plugins] Add Attach capabilities to ScriptedProcess

This patch adds process attach capabilities to the ScriptedProcess
plugin. This doesn't really expects a PID or process name, since the
process state is already script, however, this allows to create a
scripted process without requiring to have an executuble in the target.

In order to do so, this patch also turns the scripted process related
getters and setters from the `ProcessLaunchInfo` and
`ProcessAttachInfo` classes to a `ScriptedMetadata` instance and moves
it in the `ProcessInfo` class, so it can be accessed interchangeably.

This also adds the necessary SWIG wrappers to convert the internal
`Process{Attach,Launch}InfoSP` into a `SB{Attach,Launch}Info` to pass it
as argument the scripted process python implementation and convert it
back to the internal representation.

rdar://104577406

Differential Revision: https://reviews.llvm.org/D143104

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

lldb/test/API/functionalities/scripted_process/TestScriptedProcess.py

@@ -137,8 +137,14 @@ class ScriptedProcesTestCase(TestBase):
 
         target_1 = self.dbg.CreateTarget(self.getBuildArtifact("a.out"))
         self.assertTrue(target_1, VALID_TARGET)
+
+        # We still need to specify a PID when attaching even for scripted processes
+        attach_info = lldb.SBAttachInfo(42)
+        attach_info.SetProcessPluginName("ScriptedProcess")
+        attach_info.SetScriptedProcessClassName("dummy_scripted_process.DummyScriptedProcess")
+
         error = lldb.SBError()
-        process_1 = target_1.Launch(launch_info, error)
+        process_1 = target_1.Attach(attach_info, error)
         self.assertTrue(process_1 and process_1.IsValid(), PROCESS_IS_VALID)
         self.assertEqual(process_1.GetProcessID(), 42)
         self.assertEqual(process_1.GetNumThreads(), 1)