fix(files): add name attribute to default view radio group

[boris324]

Fixes #58729

Summary

Added name="default_view" to the NcRadioGroup component in FilesAppSettingsGeneral.vue so the underlying radio buttons are properly grouped with a shared name attribute.

This enables keyboard navigation between radio options using arrow keys, improving accessibility as described in the HTML radio button spec.

Test plan

1. Open Files app settings
2. Navigate to "Default view" radio buttons with keyboard
3. Verify arrow keys now switch between "All files" and "Personal files"

[susnux]

NcRadioGroup does not have such a property:
https://nextcloud-vue-components.netlify.app/#/Components/NcRadioGroup?id=ncradiogroup-1

Also it will then here be applied on a div HTML element which is invalid HTML.

It should be implemented for that component in the library (nextcloud-vue) first to properly pass it to the input element.

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[susnux]

Closing due to lack of activity.
Please add such prop first to nextcloud-vue :)