Fixes #37011

Fixes #14985

Provide an ITerminalInstance.onLineData internal API

- While installing from zip
- While syncing with gallery

Fixes #29840

deco - use correct/overwrite decorations in scm viewlet because the same URI can have multiple decorations

Only restore expansion state when there are items.

When a debugger needs more time while stepping, the tree will go empty first
(while running) and then come back with data (when stopped again). This
modifies the change for #16031 to allow the tree to properly restore
state in case a debugger needs more time providing content.

The expanded state is saved in a global variable. A check ensures that an
intermittent empty tree does not override the global variable. Future refreshes
of an empty tree will then restore the expanded state of variables.

fixes #36963