Unfortunately I don't think it's implicitly possible, and I'm not sure it's possible via a plugin either. SHIFT is a modifier key, which means it usually does something in combination with other keys. Even in IJ, if you look at the keymap, there is no shortcut assigned to Search everywhere
, so it's probably implemented as a custom feature (maybe not so relevant, but it's also not disabled if you assign a shortcut).

There are plugins which reproduce the IJ keymap in Eclipse, such as IntelliJIdeaKeymap4Eclipse (There could possibly others which I don't know yet) but not all features are supported (see below).

I haven't developed any Eclipse plugins so I don't know the limitations of the framework, so I guess it may be worth trying to contact the author of the above plugin and ask about the feature, or search alternative plugins.