Build <textarea> with text_area helper
This commit refactors the View layer’s notes#new template by replacing
a hard-coded <textarea> element with an invocation to
text_area.
First, we modify the form_with call to yield a FormBuilder instance
to the block.
Next, we invoke FormBuilder#text_area and pass :content as the first
argument. This constructs a <textarea> element with
id="content" and name="content". Since our previous
commits depended on both the id and name attributes’ presence, it’s
helpful to emphasize that the FromBuilder#text_area will generate the
necessary HTML.
When we run the test again, it is still passing.