Move suggestions::ImageFetcher into its own separate component
...so that we'll be able to reuse it from components/ntp_snippets

BUG=584429

Review-Url: https://codereview.chromium.org/1918823008
Cr-Commit-Position: refs/heads/master@{#390619}
31 files changed