Introduce selectable action / icon by the end of our row component

Let's introduce the ability to wrap an editable value in our `Row` component with our `Selector` component. This is needed by the accounts team to build [a flow for editing transaction speeds / network fees](https://github.com/MetaMask/metamask-extension/issues/29265).

Start by locating the TypeScript definitions and usages of the Row and Selector components, then read the linked issue about editing transaction speeds and network fees. Confirm how editable values are currently rendered and what the accounts flow requires. Done means Row supports the requested selectable action or icon and the relevant flow can use it.

Written by the indexing model from the issue text.