Include 'Add ground terminal' in ribbon when terminal strip is selected, and 'Insert ground terminal' when termina strip element is selected.

Details: <p>Testing:</p><p>- Open a terminal strip view.</p><p>- Select the terminal strip, and reach &#39;Create/Add&#39; tab.</p><p>- You should have &#39;New ground terminal&#39; in there.&nbsp; Click it.</p><p>- If a ground terminal is added.&nbsp; We&#39;re good.</p><p>- Do the same when a terminal from the terminal strip is selected.&nbsp; You should have &#39;Insert ground terminal&#39;.&nbsp; if it is inserted at the selected terminal&#39;s position, we&#39;re good.</p>