[platform-ui-dev] Remove ITrimManager and IWindowTrim?

[Brian de Alwis <briandealwis@xxxxxxxxx>]

ITrimManager/IWindowTrim is an internal API and doesn’t work in 4.x (as part of bug 365625).  I suggest we remove it as the API is flawed: it assumes the trim widgets have already been created against the WorkbenchWindow’s Shell.

Since it was internal, do we need to mark it for deprecation?  It’s been unimplemented for years (WorkbenchWindow#getTrimManager() returns null), so nobody can be using it anyways.

Brian.