fix(@angular/cli): resolve relative schematic from angular.json instead of current working directory

Relative schematics referenced in `angular.json` `schematicCollections` and `defaultCollection` were always resolved from the current working directory, which is not correct and caused the collection not to be resolved when the this is different from the location of the workspace config.

Closes #23136

Author: alan-agius4

packages/angular/cli/models/schematic-command.ts

@@ -21,6 +21,7 @@ import {
 } from '@angular-devkit/schematics/tools';
 import * as inquirer from 'inquirer';
 import * as systemPath from 'path';
+import { resolve } from 'path';
 import { colors } from '../utilities/color';
 import { getProjectByCwd, getSchematicDefaults, getWorkspace } from '../utilities/config';
 import { parseJsonSchemaToOptions } from '../utilities/json-schema';
@@ -373,20 +374,26 @@ export abstract class SchematicCommand<
   }
 
   protected async getDefaultSchematicCollection(): Promise<string> {
+    // Resolve relative collections from the location of `angular.json`
+    const resolveRelativeCollection = (collectionName: string) =>
+      collectionName.charAt(0) === '.'
+        ? resolve(this.context.root, collectionName)
+        : collectionName;
+
     let workspace = await getWorkspace('local');
 
     if (workspace) {
       const project = getProjectByCwd(workspace);
       if (project && workspace.getProjectCli(project)) {
         const value = workspace.getProjectCli(project)['defaultCollection'];
         if (typeof value == 'string') {
-          return value;
+          return resolveRelativeCollection(value);
         }
       }
       if (workspace.getCli()) {
         const value = workspace.getCli()['defaultCollection'];
         if (typeof value == 'string') {
-          return value;
+          return resolveRelativeCollection(value);
         }
       }
     }
@@ -395,7 +402,7 @@ export abstract class SchematicCommand<
     if (workspace && workspace.getCli()) {
       const value = workspace.getCli()['defaultCollection'];
       if (typeof value == 'string') {
-        return value;
+        return resolveRelativeCollection(value);
       }
     }