Downloading vanilla jar offline

### Enhancement Type

A completely new feature

### Describe the enhancement

when i run a paper server ,it need lots of time Downloading vanilla jar to cache dir

```
[init] Running as uid=1000 gid=1000 with /data as 'drwxrwxr-x 4 1000 1000 4096 Dec 16 14:41 /data'
[init] Resolved version given 1.17.1 into 1.17.1
[init] Resolving type given PAPER
[init] Removing old PaperMC versions ...
[init] Downloading PaperMC 1.17.1 (build 381) ...
[init] Copying plugins over...
[init] server.properties already created, skipping
[init] Updating ops
[init] Checking for JSON files.
[init] Setting initial memory to 1G and max to 1G
[init] Starting the Minecraft server...
Downloading vanilla jar...
```

why can not i use a offline vanilla jar file?

The issue names Paper and the vanilla jar download but does not identify any file, test, or entry point. Start by locating the startup code that downloads the vanilla jar and determine how an offline jar should be selected; done would require a defined offline workflow and coverage for it.

Written by the indexing model from the issue text.