Fixes https://github.com/flutter/flutter/issues/130668

Fixes https://github.com/flutter/flutter/issues/129969 by making tooltip text unselectable (for now). 
Also fixes some other issues uncovered when I was writing the tests.

Currently `getTransformTo` only works on ancestors. I'll try to add a new method that computes the transform from 2 arbitrary render objects in the same render tree in a follow-up PR and make `Selectable` use that method instead.

Fixes https://github.com/flutter/flutter/issues/129025

Also 
- simplifies OverlayPortal code a bit and adds an assert.
-  `Tooltip` shouldn't rebuild when hiding/showing the tooltip

It's time to say good bye to an old friend. 
It has outlived its usefulness.
Farewell, AbstractNode! 🫡

Fixes https://github.com/flutter/flutter/issues/123218

Bump lower Dart SDK constraints to 3.0 & add class modifiers

`OverlayPortal` 

* Reland "Overlay always applies clip (#113770)"

This reverts commit d0afbd72.

* Root navigator will not clip

* dart fix --apply

* manual fixes

* Add LookupBoundary to Overlay

* fix analysis

This reverts commit 103a5c98.

* Use `curly_braces_in_flow_control_structures` for `widgets`

* fix comments

* fix comments

This reverts commit d056500b.

This reverts commit 31de052e.

This reverts commit e2490f29.

This reverts commit 437ff210.