#61669 [13.x] Add `createQuietly` and `createManyQuietly` to `BelongsToMany`

Calling createQuietly() on a many-to-many relation doesn't throw, but the model never gets attached:

$post->tags()->createQuietly(['name' => 'php']);

$post->tags()->count(); // 0

BelongsToMany doesn't have createQuietly(), so the call falls through to the query builder, which creates the tag without attaching it.