Reland "[lldb][target] Add progress report for wait-attaching to process" (llvm#144810)

This relands commit e0933ab. The
original commit was causing the test TestCreateAfterAttach.py to fail on
ARM Ubuntu bots. It's possible that this could've been happening because
the test for wait-attach progress reporting is waiting on a process
named "a.out" which could be too generic as multiple other tests (when
run in parallel on the bots) could also be using processes named
"a.out". This commit changes the wait-attach progress report test to
wait on a unique process name.

Original PR description:

This commit adds a progress report when wait-attaching to a process as
well as a test for this.

Original PR link: llvm#144768

Author: chelcassanova

lldb/source/Target/Target.cpp

@@ -3546,6 +3546,7 @@ llvm::Expected<TraceSP> Target::GetTraceOrCreate() {
 }
 
 Status Target::Attach(ProcessAttachInfo &attach_info, Stream *stream) {
+  Progress attach_progress("Waiting to attach to process");
   m_stats.SetLaunchOrAttachTime();
   auto state = eStateInvalid;
   auto process_sp = GetProcessSP();

lldb/test/API/functionalities/progress_reporting/TestProgressReporting.py

@@ -2,6 +2,7 @@
 Test that we are able to broadcast and receive progress events from lldb
 """
 import lldb
+import threading
 
 import lldbsuite.test.lldbutil as lldbutil
 
@@ -16,6 +17,39 @@ def setUp(self):
             self.broadcaster, lldb.SBDebugger.eBroadcastBitProgress
         )
 
+    def test_wait_attach_progress_reporting(self):
+        """Test that progress reports for wait attaching work as intended."""
+        self.build()
+        target = self.dbg.CreateTarget(None)
+
+        # Wait attach to a process, then check to see that a progress report was created
+        # and that its message is correct for waiting to attach to a process.
+        class AttachThread(threading.Thread):
+            def __init__(self, target):
+                threading.Thread.__init__(self)
+                self.target = target
+
+            def run(self):
+                self.target.AttachToProcessWithName(
+                    lldb.SBListener(),
+                    "wait-attach-progress-report",
+                    True,
+                    lldb.SBError(),
+                )
+
+        thread = AttachThread(target)
+        thread.start()
+
+        event = lldbutil.fetch_next_event(self, self.listener, self.broadcaster)
+        progress_data = lldb.SBDebugger.GetProgressDataFromEvent(event)
+        message = progress_data.GetValueForKey("message").GetStringValue(100)
+        self.assertEqual(message, "Waiting to attach to process")
+
+        # Interrupt the process attach to keep the test from stalling.
+        target.process.SendAsyncInterrupt()
+
+        thread.join()
+
     def test_dwarf_symbol_loading_progress_report(self):
         """Test that we are able to fetch dwarf symbol loading progress events"""
         self.build()