[lldb] Rename lldb-vscode to lldb-dap (#69264)

Rename lldb-vscode to lldb-dap. This change is largely mechanical. The
following substitutions cover the majority of the changes in this
commit:

  s/VSCODE/DAP/
  s/VSCode/DAP/
  s/vscode/dap/
  s/g_vsc/g_dap/

Discourse RFC:
https://discourse.llvm.org/t/rfc-rename-lldb-vscode-to-lldb-dap/74075/