Use the new VSC API to trust output

[DonJayamanne]

See here microsoft/vscode#108946 (comment) & microsoft/vscode#109104

We must change the existing code to use the new VSC API, as current approach is very hacky
(when we trust a notebook, we perform an edit and prevent VSCode from seeing it as a dirty change & force it to reload the notebook).
Hopefully with the new VSC API - all we need to do is just update a single property

[DonJayamanne]

Block due to microsoft/vscode#114936

[kieferrm]

The upstream issues is closed.

[DonJayamanne]

Closing this as we've done what needs to be done, and we'll update the changes when there are new changes to propopsed API and workspace trust.