Search bar input should span multiple rows

[MrOrz]

As-is

The search input in search page is only 1 line high

To-be

As in spec, the search input should grow as input.

This should be achievable using Material UI's Textarea autosize.

[MrOrz]

From discussions in https://g0v.hackmd.io/OC7BneJ3TEGJHge1hWV-0w?both#%E6%9C%AA%E7%AB%9F%E9%A0%85%E7%9B%AE
even though we can support multi-line, "enter" should still trigger search instead of new lines