- The module is edited by changing the AST, not the text representation.
- `IdMap`s no longer need to be maintained in parallel with the module content; they are snapshots produced as needed from the ASTs.
- Simplistic synchronization is in place until #8237: Edits are never merged; if two edits are started from the same state, one will be overwritten.
Introduce new AST type; use it to replace current uses of AstExtended; for now edits and synchronization are implemented on the old mechanisms (text edits / RelativeRange id map).
# Important Notes
- Edit-related code is commented out until the next PR because it is incompatible with the transitional IdMap-based synchronization.
Fixes#8252
As we use proper alias analysis, we no longer display connections to overshadowed identifiers.
# Important Notes
I've changed the meaning of edge's "source" - now it's expression ID of the constituted identifier, not the node ID. This will allow proper handling nodes like `[x, y] = Main.get_point` once the engine will support them.
