feat(@angular/cli): show optional migrations during update process

[alan-agius4]

When running ng update we now display optional migrations from packages.

When the terminal is interactive, we prompt the users and ask them to choose which migrations they would like to run.

$ ng update @angular/core --from=14 --migrate-only --allow-dirty
Using package manager: yarn
Collecting installed dependencies...
Found 22 dependencies.
** Executing migrations of package '@angular/core' **

▸ Since Angular v15, the `RouterLink` contains the logic of the `RouterLinkWithHref` directive.
  This migration replaces all `RouterLinkWithHref` references with `RouterLink`.
  Migration completed (No changes made).

** Optional migrations of package '@angular/core' **

This package have 2 optional migrations that can be executed.
Select the migrations that you'd like to run (Press <space> to select, <a> to toggle all, <i> to invert selection, and <enter> to proceed)
❯◯ Update server builds to use generate ESM output.
 ◯ Lorem ipsum dolor sit amet, consectetur adipiscing elit.

In case the terminal is non interactive, we will print the commands that need to be executed to run the optional migrations.

$ ng update @angular/core --from=14 --migrate-only --allow-dirty
Using package manager: yarn
Collecting installed dependencies...
Found 22 dependencies.
** Executing migrations of package '@angular/core' **

▸ Since Angular v15, the `RouterLink` contains the logic of the `RouterLinkWithHref` directive.
  This migration replaces all `RouterLinkWithHref` references with `RouterLink`.
  Migration completed (No changes made).

** Optional migrations of package '@angular/core' **

This package have 2 optional migrations that can be executed.

▸ Update server builds to use generate ESM output.
  ng update @angular/core --migration-only --name esm-server-builds

▸ Lorem ipsum dolor sit amet, consectetur adipiscing elit.
  ng update @angular/core --migration-only --name migration-v15-router-link-with-href

Note: Optional migrations are defined by setting the optional property to true. Example:

{
  "schematics": {
    "esm-server-builds": {
      "version": "15.0.0",
      "description": "Update server builds to use generate ESM output",
      "factory": "./migrations/relative-link-resolution/bundle",
      "optional": true
    }
}

Closes #23205

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