[@mantine/core] add controlled search and per-list wording to transfer-list

[jvdsande]

As discussed on Discord, a few improvements to the TransferList component:

• transferIcon and transferAllIcon for customising the icons. The props take a component with a reversed props to allow handling both lists correctly.
• placeholder prop that is used in place of nothingFound if query is empty. If placeholder is omitted, nothingFound is used in its place
• searchPlaceholder, nothingFound and placeholder can now take a tuple instead of a single value, to customize each panel independently. A single value can still be passed, in which case it's applied to both panels.
• searchValues and onSearch props allowing to control the searches

[rtivital]

Thanks!