[lldb][test] Remove symlink for API tests.

Summary: Moves lldbsuite tests to lldb/test/API.

This is a largely mechanical change, moved with the following steps:

```
rm lldb/test/API/testcases
mkdir -p lldb/test/API/{test_runner/test,tools/lldb-{server,vscode}}
mv lldb/packages/Python/lldbsuite/test/test_runner/test lldb/test/API/test_runner
for d in $(find lldb/packages/Python/lldbsuite/test/* -maxdepth 0 -type d | egrep -v "make|plugins|test_runner|tools"); do mv $d lldb/test/API; done
for d in $(find lldb/packages/Python/lldbsuite/test/tools/lldb-vscode -maxdepth 1 -mindepth 1 | grep -v ".py"); do mv $d lldb/test/API/tools/lldb-vscode; done
for d in $(find lldb/packages/Python/lldbsuite/test/tools/lldb-server -maxdepth 1 -mindepth 1 | egrep -v "gdbremote_testcase.py|lldbgdbserverutils.py|socket_packet_pump.py"); do mv $d lldb/test/API/tools/lldb-server; done
```

lldb/packages/Python/lldbsuite/__init__.py and lldb/test/API/lit.cfg.py were also updated with the new directory structure.

Reviewers: labath, JDevlieghere

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D71151

lldb/test/API/python_api/default-constructor/sb_thread.py

@@ -0,0 +1,38 @@
+"""
+Fuzz tests an object after the default construction to make sure it does not crash lldb.
+"""
+
+import lldb
+
+
+def fuzz_obj(obj):
+    obj.GetStopReason()
+    obj.GetStopReasonDataCount()
+    obj.GetStopReasonDataAtIndex(100)
+    obj.GetStopDescription(256)
+    obj.GetThreadID()
+    obj.GetIndexID()
+    obj.GetName()
+    obj.GetQueueName()
+    obj.StepOver(lldb.eOnlyDuringStepping)
+    obj.StepInto(lldb.eOnlyDuringStepping)
+    obj.StepOut()
+    frame = lldb.SBFrame()
+    obj.StepOutOfFrame(frame)
+    obj.StepInstruction(True)
+    filespec = lldb.SBFileSpec()
+    obj.StepOverUntil(frame, filespec, 1234)
+    obj.RunToAddress(0xabcd)
+    obj.Suspend()
+    obj.Resume()
+    obj.IsSuspended()
+    obj.GetNumFrames()
+    obj.GetFrameAtIndex(200)
+    obj.GetSelectedFrame()
+    obj.SetSelectedFrame(999)
+    obj.GetProcess()
+    obj.GetDescription(lldb.SBStream())
+    obj.Clear()
+    for frame in obj:
+        s = str(frame)
+    len(obj)