Angular Schematics - Apply thousands of changes on tree cause error "Maximum call stack size exceeded"

# 🐞 Bug report

### Description

I use Angular Schematics to migrate from AngularJs to Angular. The application is a large one with thousands of page. I try to create a component for each page based on a template. When I try to create the component on a smaller project like 200 pages it's working but when I fall on a large one with more than 1000 pages (1000 schematics rules)

## 🔬 Minimal Reproduction

export function createPageComponents(options: any): Rule {

    return (tree: Tree, context: SchematicContext) => {

        const logger = context.logger;

        const directory = tree.getDir('my_path/pages');


        const rules: Rule[] = [];

        directory.visit((filePath) => {

            if (!filePath.endsWith('config.ts')) {

                return;

            }

            const dirPath = dirname(filePath);

            const parsedPath = parseName(dirPath, basename(filePath).split('.')[0]);

            options = {

                path: parsedPath.path,

                name: parsedPath.name

            };

            const templateSource = apply(

                url('./files'),

                [

                    applyTemplates({

                        ...strings,

                        ...options

                    }),

                    move(parsedPath.path)

                ]

            );

            const rule = mergeWith(templateSource);

            rules.push(rule);

        });

        return chain(rules);

    };

}

## 🔥 Exception or Error

    RangeError: Maximum call stack size exceeded

        at Console.warn ()

        at Observable._trySubscribe (my_path\node_modules\rxjs\internal\Observable.js:55:25)

        at Observable.subscribe (my_path\node_modules\rxjs\internal\Observable.js:30:22)

        at MergeMapOperator.call (my_path\node_modules\rxjs\internal\operators\mergeMap.js:39:23)

        at Observable.subscribe (my_path\node_modules\rxjs\internal\Observable.js:25:31)

        at MapOperator.call (my_path\node_modules\rxjs\internal\operators\map.js:32:23)

        at Observable.subscribe (my_path\node_modules\rxjs\internal\Observable.js:25:31)

        at MapToOperator.call (my_path\node_modules\rxjs\internal\operators\mapTo.js:26:23)

        at Observable.subscribe (my_path\node_modules\rxjs\internal\Observable.js:25:31)

        at DefaultIfEmptyOperator.call (my_path\node_modules\rxjs\internal\operators\defaultIfEmpty.js:27:23)

## 🌍 Your Environment

Angular CLI: 9.1.4

Node: 10.19.0

OS: win32 x64


Angular: 9.1.4

... animations, cli, common, compiler, compiler-cli, core, forms

... language-service, platform-browser, platform-browser-dynamic

... router

Ivy Workspace: Yes

Package                            Version

------------------------------------------------------------

@angular-devkit/architect          0.901.4

@angular-devkit/build-angular      0.901.4

@angular-devkit/build-ng-packagr   0.901.4

@angular-devkit/build-optimizer    0.901.4

@angular-devkit/build-webpack      0.901.4

@angular-devkit/core               9.1.4

@angular-devkit/schematics         9.1.7

@angular-devkit/schematics-cli     0.901.7

@angular/upgrade                   9.1.9

@ngtools/webpack                   9.1.4

@schematics/angular                9.1.4 (cli-only)

@schematics/schematics             0.901.7

@schematics/update                 0.901.4

ng-packagr                         9.1.3

rxjs                               6.5.5

typescript                         3.8.3

webpack                            4.42.0

Start at the createPageComponents entry point in the reproduction, especially the rules array and chain(rules), and reproduce the failure with more than 1,000 schematics rules. Read the Angular Schematics execution path alongside the RxJS stack trace shown in the report. Done means applying the large set of page-component changes without a maximum call stack error.

Written by the indexing model from the issue text.