[next] fix(NcActions): find actions deeper nested

[raimund-schluessler]

☑️ Resolves

• This fixes an issue that occured when actions are nested deeper than one level. This can happen e.g. when one puts a loop in a slot, as it happens in NcDashboardWidgetItem, i.e.:

<NcActions>
	<slot name="actions">
		<NcActionButton v-for="action in actions">
			{{ action.text }}
		</NcActionButton>
	</slot>
</NcActions>

These actions were nested two levels deep in two Fragments and were not found with the old logic, causing the action menu to be empty. I changed the logic to be recursive now, finding all actions.

As this occurred in NcDashboardWidgetItem, it is included here as well.

[raimund-schluessler]

Could we get this reviewed?

[raimund-schluessler]

@susnux Would you have time to review this PR, maybe?

[raimund-schluessler]

Fixed the conflict. @susnux Mind reviewing this as well, please?