[dotnet, golang] Connot access to extension SDK despite it being installed and FLATPAK_ENABLE_SDK_EXT being used

I installed VSCode through Flatpak, and followed the instruction in the first run text file, but VSCode as well as VScode-OSS both do not detect the Flatpak sdk extension.

I tried both `FLATPAK_ENABLE_SDK_EXT=dotnet` and `FLATPAK_ENABLE_SDK_EXT=dotnet7` before `flatpak run com.visualstudio.code`, both returned ` Requested SDK extension "dotnet" is not installed`

Installed SDKs:
```
$ flatpak list | grep -i sdk
Freedesktop SDK org.freedesktop.Sdk 22.08.15 22.08 flathub system
.NET Core SDK extension org.freedesktop.Sdk.Extension.dotnet7 7.0.401 23.08 flathub system
Go programming language Sdk extension org.freedesktop.Sdk.Extension.golang 1.21.0 23.08 flathub system
```

Same problem with the golang extenssion and `FLATPAK_ENABLE_SDK_EXT=golang`

In all cases `/usr/lib/sdk/` is empty.

Edit: the command `$ find / -iname dotnet` returns no result when executed inside the container.

Edit2: Something noteworthy I ended up finding is that the dotnet6 sdk do work as intended, but both dotnet5, dotnet7 and golang don't.

首先使用 `FLATPAK_ENABLE_SDK_EXT=dotnet` 和 `golang` 复现报告中的 `flatpak run com.visualstudio.code` 命令，然后检查容器内的 `/usr/lib/sdk/`，并比较已安装扩展的 ID。完成标准是确定 dotnet7 和 golang 不可用而 dotnet6 可以正常工作的原因，或记录受支持的扩展配置。

由索引模型根据 Issue 内容生成。