Using `wslinfo --env` to read Windows environment variables

Nobody has claimed this yet.

**PROBLEM**
Currently, one of the most practical methods for accessing Windows environment variables in WSL is by listing the required variables in `WSLENV` on the Windows host. However, this approach presents a challenge, as shell scripts running on WSL cannot modify this configuration on the host. An alternative is to read the output of commands like `cmd.exe /C set VARNAME` in Linux, but this method is inelegant and unreliable. For example, when using `sudo` to execute a script, `cmd.exe` becomes inaccessible, which requires either instructing the user to pass additional environment-related arguments to `sudo` to access the Windows `PATH`, or specifying the full path to `cmd.exe` in the script. Both of these solutions are neither elegant nor reliable.

**SOLUTION**
I believe that using `wslinfo --env` would be the most efficient and reliable method for accessing Windows environment variables within shell scripts. For example:

```
$ wslinfo --env=LOCALAPPDATA
C:\Users\john\AppData\Local

$ wslinfo --env=HOMEDRIVE
C:
```

Moreover, this command may also support the additional `-p` and `-l` flags, similar to their usage with `WSLENV`. Specifically, the `-p` flag converts a Windows path into a Linux path, while the `-l` flag converts a Windows semicolon-delimited path list into a Linux colon-delimited path list. For example:

```
$ wslinfo --env=LOCALAPPDATA
C:\Users\john\AppData\Local

$ wslinfo --env=LOCALAPPDATA -p
/mnt/c/Users/john/AppData/Local

$ wslinfo --env=PATHLIST
C:\Users\john;C:\Users\mike;C:\Users\rose

$ wslinfo --env=PATHLIST -l
/mnt/c/Users/john:/mnt/c/Users/mike:/mnt/c/Users/rose
```

Start by locating the `wslinfo` command entry point and the existing handling of `WSLENV`. Check how environment values and path conversions are exposed, then compare the behavior with the examples in this issue. Done means `wslinfo --env` reads the requested Windows variable and the proposed `-p` and `-l` conversions behave as documented.

Written by the indexing model from the issue text.