Updates for all angular.io links to the new angular.dev domain. Additionally, adjustment to new resources where the equivalent does not exist on the new site (e.g. Tour of Heroes tutorial)
By using the `strings` re-export from `@angular-devkit/schematics` instead of from `@angular-devkit/core`,
the number of imports from `@angular-devkit/core` has been reduced and lowers the direct dependency count
for many of the individual schematics.
Currently when using `ivy-ngcc` it will print out a warning
```
Failed to read entry point info from //node_modules/@schematics/angular/workspace/files/package.json with error SyntaxError: Unexpected token < in JSON at position 1121.
```
Fixes#13378
