[lldb-dap] Create symlink lldb-vscode pointing to lldb-dap

Summary: Add a symlink `lldb-vscode` pointing to `lldb-dap` so that our VSCode integration works without updating anything. This is needed as the toolchain won't reach all users at the same time, and updating VSCode will also take time to reach user machines.

Test Plan:
I can see the symlink in install folder
{F1149366304}

Reviewers: xiaojingtang, #lldb_team

Reviewed By: xiaojingtang

Subscribers: #lldb_team

Differential Revision: https://phabricator.intern.facebook.com/D51275683

Author: kusmour

lldb/tools/lldb-dap/CMakeLists.txt

@@ -89,3 +89,5 @@ if(LLDB_DAP_WELCOME_MESSAGE)
 endif()
 
 add_subdirectory(tool)
+
+add_llvm_tool_symlink(lldb-vscode lldb-dap)