Add the ability to pin rows in the Profile Memory table

[kenzieschmoll]

In trying to debug a memory leak I found myself wanting to pin classes to the top of the Profile memory view like we support for the Trace Instances view:

A checkbox UI probably doesn't make sense for the Profile Memory view, but perhaps a Pin icon would be better.

[EclipseAditya]

Hi, I would like to work on this issue, Can you please assign it to me. Thanks!