feat(view): add default value support for renderSection()

[gilberthtg]

This commit extends the View::renderSection() method to allow an optional default value parameter when a section is not found or is empty.

• Added a new $defaultContent argument to renderSection()
• If the requested section is missing or empty, the method will return the provided default value instead of an empty string
• Preserves existing behavior when $defaultContent is not set

This improvement makes it easier to provide fallback content in layouts without requiring additional wrapper logic in user applications.

Example usage:
renderSection('example', false, '

Default form content

') ?>

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value (without duplication)
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[mergeable]

Hi there, gilberthtg! 👋

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[michalsn]

While I understand what this change does, I'm not sure in which situations it would be useful. Let's see what others think.

@gilberthtg Please follow the mergeable bot instructions.

• New features should go to the 4.7 branch.
• We need tests for this
• We need an updated user guide, so that this will not become a secret feature
• We need a changelog entry

[neznaika0]

Is it much better than the condition?

<?php $this->renderSection('base') ?? 'Default HTML' ?>

The question is interesting. But the solution to insert a backup HTML should look different. My opinion. The problem is the poor readability of the default code when it has logic or contains a large amount of code.