fix pinning topSites not respecting position

[cezaraugusto]

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Ran git rebase -i to squash commits (if needed).

Auditors: @bsclifton

fix #5337

Test Plan:

• Access new tab page;
• Access 4-6 websites;
• Pin the second and fourth site.;
• Pinning a site should add a Pin icon on top-right corner and be kept on its position (not jump);
• Access another website (i.e. https://brave.com) and get back to new tab.
• Ensure that pinned topSites are still on their positions (2nd and 4th);
• Ensure that your latest accessed site is on first position;
• Ensure that other sites were pulled to right, but skipping pinned positions.

[bsclifton]

LGTM 😄

[srirambv]

Ensure that your latest accessed site is on first position

visiting a new site puts the tile in between the two pinned tiles and not in first position.

[cezaraugusto]

@srirambv could you open a new issue for that? This is more related to how we define topSites (based on number of visits). On your comment pinned topSites are still on their positions, so slightly different. Thanks!!