Add model and migration for LocationPaymentSettings

[pdbreen]

Migration:

Schema::create('location_payment_settings', function (Blueprint $table) {
    $table->id();
    $table->foreignIdFor(Location::class)->unique();	// NOTE - unique() added -- there should be exactly one record per location!
    $table->string('stripe_publishable')->nullable()->unique();
    $table->text('stripe_secret')->nullable();
    $table->foreignIdFor(app('user'), 'creator_id');
    $table->foreignIdFor(app('user'), 'updater_id');
    $table->timestamps();
});

Create corresponding LocationPaymentSettings model, factory and test. Package tipoff/locations should become a required dependency as part of this.