[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/watchpoint/condition/main.cpp

@@ -0,0 +1,27 @@
+//===-- main.c --------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#include <stdio.h>
+#include <stdint.h>
+
+int32_t global = 0; // Watchpoint variable declaration.
+
+static void modify(int32_t &var) {
+    ++var;
+}
+
+int main(int argc, char** argv) {
+    int local = 0;
+    printf("&global=%p\n", &global);
+    printf("about to write to 'global'...\n"); // Set break point at this line.
+                                               // When stopped, watch 'global',
+                                               // for the condition "global == 5".
+    for (int i = 0; i < 10; ++i)
+        modify(global);
+
+    printf("global=%d\n", global);
+}