Update nvmrc to node 8

Fix updating comment positions

As noted in [the wiki](https://github.com/Microsoft/vscode/wiki/How-to-Contribute#prerequisites) node's version should be larger than 8.12 so 8.9.2 will not work.

In fact, I think we only need to define the target version as `8` so we can have the latest version that satisfies the requirement (`>= 8.12.0, < 9.0.0`). At the time of writing it is `8.15` which works perfectly fine (install + watch + run).

Detect md image link

Fix #52562, Process Explorer: NVDA reads the whole table dimension every time before reading each cell value

Fixes #67138

fixes  #67018

fyi @joaomoreno

* ObjectTree/List: Add ariaRootRole option.  Addresses: #65939

* Address @joaomoreno tweaks

fixes #67063

fixes #67075

fixes  #67062