fix(windows): access violation closing text editor

Fixes #4848.

This error arose because the form was destroyed after kmshell.dpr
completes, which meant that sentry had already been destroyed. The
sentry call was simply to record a breadcrumb of the form being closed.

The fix is to move the lifecycle of the form into the `OpenTextEditor`
function. `OpenTextEditor` is used only by `initprog.RunKMCOM` and so it
is safe to remove the ApplicationRunning path of the code, which
simplifies the lifecycle of the form.