Feature: #99806 - Introduce GenericButton component

Description

A new component \TYPO3\CMS\Backend\Template\Components\Buttons\GenericButton is introduced that allows to render any markup in the module menu bar.

Example:

$buttonBar = $this->moduleTemplate->getDocHeaderComponent()->getButtonBar();
$genericButton = GeneralUtility::makeInstance(GenericButton::class)
    ->setTag('a')
    ->setHref('#')
    ->setLabel('Label')
    ->setTitle('Title')
    ->setIcon($this->iconFactory->getIcon('actions-heart'))
    ->setAttributes(['data-value' => '123']);
$buttonBar->addButton($genericButton, ButtonBar::BUTTON_POSITION_RIGHT, 2);