[Enhancement] Create cache in a user directory

還沒有人認領這個 Issue。

### How are you using the lua-language-server?

Neovim

### Which OS are you using?

Linux

### What is the issue affecting?

Other

### Expected Behaviour

`lua-language-server` should create the cache directory on the user's home directory. On Linux this should be in `~/.cache/lua-language-server/` ideally.

### Actual Behaviour

`lua-language-server` fails to start because it attempts to create the cache directory in a system directory which a regular user doesn't have permissions to write to.

### Reproduction steps

1. Download `lua-language-server-3.9.1-linux-x64.tar.gz` and extract it to `/opt/lua-language-server/`
2. Make sure the owner of `/opt/lua-language-server/` is `root:root`.
3. Execute `/opt/lua-language-server/bin/lua-language-server --help`
4. See error: `lua-language-server: create_directories: "/opt/lua-language-server/log/cache/40815": (generic:13)Permission denied`

### Additional Notes

_No response_

### Log File

_No response_

從重現 `/opt/lua-language-server/bin/lua-language-server --help` 開始，並追蹤 `log/cache/40815` 路徑在哪裡被選取。確認對一般 Linux 使用者而言，快取會建立在 `~/.cache/lua-language-server/` 下，然後在沒有權限錯誤的情況下重新執行文件中記載的啟動步驟。

由索引模型根據 Issue 內容生成。