CLI generates items in unexpected workspace directories

# 🐞 Bug report

### Command

- [x] generate

### Description

In a multi-project workspace, `ng generate` creates items (components, etc.) based on the current directory, rather than `[ProjectRoot]/src/app` or `[ProjectRoot/src/lib`.

In a single-project workspace, the CLI knows to place items inside of `src...`. However, in a multi-project workspace with a `projects/...` directory structure, the developer must navigate to `src/app` or `src/lib` prior to generating the item, or specify its location, such as:
```
cd ./projects/app1/src/app
ng generate component component1
```

or

```
cd ./projects/app1
ng generate component src/app/component1 -module src/app/app
```

The expectation would be to navigate to the root of the project, then generate items in the same manner as a single-project workspace, such as:

```
cd ./projects/app1
ng generate component component1
```

Ideally, developers would not have to worry about where they are within the project directory structure or having to specify the location of the module (particularly in default module configurations).

## 🌍 Your Environment

Angular CLI: 12.2.2

Node: 14.16.0

Package Manager: npm 7.21.0

OS: win32 x64


Angular: 12.2.2

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

... forms, material, platform-browser, platform-browser-dynamic

... router

Package                         Version

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

@angular-devkit/architect       0.1202.2

@angular-devkit/build-angular   12.2.2

@angular-devkit/core            12.2.2

@angular-devkit/schematics      12.2.2

@schematics/angular             12.2.2

ng-packagr                      12.2.0

rxjs                            6.6.7

typescript                      4.3.5

Beginne damit, die `ng generate component component1`-Befehle aus einem Workspace mit mehreren Projekten nachzustellen, und vergleiche die Generierung aus dem Projektstammverzeichnis mit der Generierung aus `src/app` oder `src/lib`. Die Aufgabe ist abgeschlossen, wenn die Generierung aus dem Projektstammverzeichnis Elemente im erwarteten Quellverzeichnis des Projekts ablegt und das Modul auflöst, ohne einen expliziten Pfad zu erfordern.

Vom Indexierungsmodell aus dem Issue-Text verfasst.