[vscode-lldb] Restart server when lldb-dap binary has changed (#159797)

# Motiviation

This helps the development of the lldb-dap binary. For example, when
testing a locally built lldb-dap binary, one probably wants to restart
the server after each build in order to use the latest binary. Not doing
so leads to confusion like "why the new lldb-dap isn't doing what I just
changed?".

This patch adds dependency to the `chokidar` package. The reason is that
we need something to detect changes to the `lldb-dap` binary file and
`chokidar` appears to be the most reliable package to do so. An
alternative solution which doesn't require adding dependencies is
discussed below (solution 1).

# Two different solutions considered

Solution 1: Restart server when lldb-dap binary's modification time
changes. https://github.com/llvm/llvm-project/pull/159481 implements
solution 1.

Solution 2: Restart server when lldb-dap binary has changed (as detected
by a file system watcher). This patch implements solution 2 (using
`chokidar`).

# This patch (solution 2)

If the lldb-dap binary has changed, the next time the user start a debug
session, a dialog box will show up and prompt the user to restart the
server. Depend on what has changed, the dialog box will show different
content (see below)

* When both the lldb-dap binary and the arguments have changed:
<img width="520" height="357" alt="diff_args_and_binary"
src="https://github.com/user-attachments/assets/6580e05f-05c3-4d80-8c1a-9c3abf279218"
/>

* When only the lldb-dap binary has changed:
<img width="260" height="384" alt="diff_binary"
src="https://github.com/user-attachments/assets/933b8987-9c21-44f3-ad68-57b8eeb58525"
/>

* When only the arguments have changed (existing):
<img width="520" height="343" alt="diff_args"
src="https://github.com/user-attachments/assets/c0e6771c-ad32-4fb8-b5df-b34cce48ed1a"
/>