refactor(@schematics/angular): improve automatic versions

With this change we improve the versions we set in the users project to be less confusing.  Previously, for both stable and next versions we set the versions of Angular packages to the below;

```
"@angular/animations": "~12.2.0-"
```

This might be problematic as one might not immediately notice that they might depend on a prerelease. The `-` is short character and can be missed when having a large set of dependencies.

With this can we are more explicate by adding `--next` when it's a prerelease and omit the suffix for stable releases.

Author: alan-agius4

packages/schematics/angular/utility/latest-versions.ts

@@ -7,15 +7,15 @@
  */
 
 /** Retrieve the minor version for the provided version string. */
-function getEarliestMinorVersion(version: string) {
-  const versionMatching = version.match(/^(\d+)\.(\d+)\.*/);
+function getAngularEarliestMinorVersion(version: string): string {
+  const versionMatching = version.match(/^(\d+)\.(\d+)\.\d+(-\w+)?/);
 
   if (versionMatching === null) {
     throw Error('Unable to determine the minor version for the provided version');
   }
-  const [_, major, minor] = versionMatching;
+  const [_, major, minor, prerelease = ''] = versionMatching;
 
-  return `${major}.${minor}.0`;
+  return `~${major}.${minor}.0${prerelease}`;
 }
 
 export const latestVersions: Record<string, string> & {
@@ -27,9 +27,7 @@ export const latestVersions: Record<string, string> & {
   ...require('./latest-versions/package.json')['dependencies'],
 
   // As Angular CLI works with same minor versions of Angular Framework, a tilde match for the current
-  // Angular CLI minor version with earliest prerelease (appended with `-`) will match the latest
-  // Angular Framework minor.
-  Angular: `~${getEarliestMinorVersion(require('../package.json')['version'])}-`,
+  Angular: getAngularEarliestMinorVersion(require('../package.json')['version']),
 
   // Since @angular-devkit/build-angular and @schematics/angular are always
   // published together from the same monorepo, and they are both