fix(core): init should use pr version when specified (#30497)

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## Current Behavior
`nx init` always either installs `next` or `latest` versions of Nx. The
intent here is that running `npx nx init` should always provide the
latest version of Nx, and we added a condition to use `next` if we
detected a beta version of Nx was running to facilitate easier testing
of RC and beta releases. The full logic to determine which version of Nx
to setup is below:

```ts
const version =
    process.env.NX_VERSION ?? (prerelease(nxVersion) ? 'next' : 'latest');
```

The goal here was to avoid hitting the `npx` cache and accidentally
creating new workspaces with an older Nx version. This logic falls apart
a bit when considering prereleases though, as `npx nx@next init` would
always check the tag to make sure its up to date rather than using a
cached version. This is the case when providing **_any_** tag to `npx`.

A bad side effect of the above is that when trying to test PR builds and
the like, `nx init` will never setup the PR build when running `npx
[email protected]....` opting instead to setup `next`.

## Expected Behavior
Running `npx [email protected].... init` sets up an nx workspace using the
specified PR release.

## Related Issue(s)
<!-- Please link the issue being fixed so it gets closed when this is
merged. -->

Fixes #

Author: AgentEnder

packages/nx/src/command-line/init/init-v1.ts

@@ -30,7 +30,7 @@ export async function initHandler(options: InitArgs) {
   const args = process.argv.slice(3).join(' ');
 
   const version =
-    process.env.NX_VERSION ?? (prerelease(nxVersion) ? 'next' : 'latest');
+    process.env.NX_VERSION ?? (prerelease(nxVersion) ? nxVersion : 'latest');
   if (process.env.NX_VERSION) {
     console.log(`Using version ${process.env.NX_VERSION}`);
   }

packages/nx/src/command-line/init/init-v2.ts

@@ -46,7 +46,7 @@ export interface InitArgs {
 export async function initHandler(options: InitArgs): Promise<void> {
   process.env.NX_RUNNING_NX_INIT = 'true';
   const version =
-    process.env.NX_VERSION ?? (prerelease(nxVersion) ? 'next' : 'latest');
+    process.env.NX_VERSION ?? (prerelease(nxVersion) ? nxVersion : 'latest');
   if (process.env.NX_VERSION) {
     output.log({ title: `Using version ${process.env.NX_VERSION}` });
   }