[6.x] Add Form builder - #19384

public function settingsForm(FormContext $context = new FormContext): ?Form
{
    return Form::make([
        Field::make(
            label: t('API key', category: 'my-plugin'),
            control: Text::make('apiKey')->value($this->apiKey),
        ),
    ]);
}

public function settingsForm(FormContext $context = new FormContext): Form
{
    return Form::make([
        Field::make(t('UI Mode'))
            ->instructions(t('How the field should be presented in the control panel.'))
            ->control(Choice::make('uiMode')->value($this->uiMode)->options([
                ['label' => t('Normal'), 'value' => 'normal'],
                ['label' => t('Enlarged'), 'value' => 'enlarged'],
            ])),
        Field::make(t('Placeholder Text'))
            ->instructions(t('The text that will be shown if the field doesn’t have a value.'))
            ->control(Text::make(['placeholder'])->value($this->placeholder)),
        Group::make('plain-text-field-limit', [
            Field::make(t('Maximum'))
                ->instructions(t('The maximum number of characters or bytes the field is allowed to have.'))
                ->control(Number::make('fieldLimit')
                    ->value($this->charLimit ?? $this->byteLimit)
                    ->deltaGroupAtNamespace()
                    ->min(1)),
            Field::make(t('Unit'))
                ->control(Choice::make(['limitUnit'])
                    ->value($this->byteLimit ? 'bytes' : 'chars')
                    ->deltaGroupAtNamespace()
                    ->options([
                        ['label' => t('Characters'), 'value' => 'chars'],
                        ['label' => t('Bytes'), 'value' => 'bytes'],
                    ])),
        ])->label(t('Field Limit')),
        Group::make('plain-text-behavior', [
            Field::make(t('Use a monospaced font'))->control(Lightswitch::make('code')->value($this->code)),
            Field::make(t('Allow line breaks'))->control(Lightswitch::make(['multiline'])->value($this->multiline)),
        ]),
        Field::make(t('Initial Rows'))
            ->control(Number::make('initialRows')
                ->value($this->initialRows)
                ->min(1)),
    ]);
}