[lldb][trace] Add a basic function call dump [1] - Add the command scaffolding

[wallace]

Summary

The command is thread trace dump function-calls and as minimum will
require printing to a file in json and non-json format

I added a test

[wallace]

nits

[persona0220]

LGTM! I'll also review the algorithm soon :)

lldb/source/Commands/CommandObjectThread.cpp

 
 protected:
   bool DoExecute(Args &args, CommandReturnObject &result) override {
     ThreadSP thread_sp = GetSingleThreadFromArgs(m_exe_ctx, args, result);
     if (!thread_sp) {
       result.AppendError("invalid thread\n");
       return false;
     }
-    result.AppendMessageWithFormatv("json = {0}, pretty_json = {1}, file = {2}",
+    result.AppendMessageWithFormatv("json = {0}, pretty_json = {1}, file = {2}, thread = {3}",
                                     m_options.m_json, m_options.m_pretty_json,
-                                    m_options.m_output_file);
+                                    !!m_options.m_output_file, thread_sp->GetID());
     return true;
   }
 
   CommandOptions m_options;
 };
 
 // CommandObjectTraceDumpInstructions
 #define LLDB_OPTIONS_thread_trace_dump_instructions

lldb/test/API/commands/trace/TestTraceDumpFunctionCalls.py

+from intelpt_testcase import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+
+class TestTraceDumpInfo(TraceIntelPTTestCaseBase):
+    def testDumpFunctionCalls(self):
+      self.expect("trace load -v " +
+        os.path.join(self.getSourceDir(), "intelpt-trace", "trace.json"))
+
+      self.expect("thread trace dump function-calls 2",
+        error=True, substrs=['error: no thread with index: "2"'])
+
+      self.expect("thread trace dump function-calls 1 -j",
+        substrs=['json = true, pretty_json = false, file = false, thread = 3842849'])
+
+      self.expect("thread trace dump function-calls 1 -F /tmp -J",
+        substrs=['false, pretty_json = true, file = true, thread = 3842849'])